Latest Research News
Here are some nut studies that link to benefits in connection with diabetes, heart disease, and inflammation. However, it should be noted that they are often very small, and usually funded by nut organizations. I wouldn't put too much weight on such.
Nuts linked to improved type 2 diabetes health
A 3-month study involving 117 older adults (mean age 62) with diabetes found that 75g of nuts (½ a cup) a day, as a replacement for carbohydrate foods, can improve glycemic control and blood lipids in those with type 2 diabetes.
The nuts used were a mixed lot of tree nuts (almonds, Brazils, cashews, hazelnuts, pecans, pine nuts, pistachios, macadamias and walnuts) and peanuts. improved blood lipid levels and blood sugar levels in individuals with non-insulin dependent diabetes.
Jenkins, D.J.A., C.W.C. Kendall, B. Lamarche, M.S. Banach, K. Srichaikul, E. Vidgen, S. Mitchell, T. Parker, S. Nishi, B. Bashyam, R. de Souza, C. Ireland, S.C. Pichika, J. Beyene, J.L. Sievenpiper, R.G. Josse, 2018. Nuts as a replacement for carbohydrates in the diabetic diet: a reanalysis of a randomised controlled trial. Diabetologia https://doi.org/10.1007/s00125-018-4628-9
Eating pecans had significant effect on biomarkers of heart disease and type 2 diabetes
A very small 4-week study involving 26 overweight and obese adults (average age 59) found that those given a diet with pecans substituted for 15% of the total calories significantly improved insulin sensitivity and had a significant effect on markers of cardiometabolic disease.
Both the control diet and the pecan-rich diet were low in fruits, vegetables and fiber.
The study entitled "A Pecan-Rich Diet Improves Cardiometabolic Risk Factors in Overweight and Obese Adults: A Randomized Controlled Trial" is available online and was presented at the American Society for Nutrition Annual Conference, Nutrition 2018 held in Boston in June.
A handful of nuts a day cuts the risk of a wide range of diseases
A review of 29 studies involving some 819,000 participants has concluded that people who eat at least 20g of nuts (a handful) a day have a 30% lower risk of heart disease, as well as lower risks of cancer, respiratory disease, and diabetes.
The study included all kinds of tree nuts, and also peanuts. The results were in general similar. There was little evidence of further improvement in health outcomes as a result of eating more than 20g of nuts.
Nuts and peanuts are high in fibre, magnesium, and polyunsaturated fats. Some nuts, particularly walnuts and pecan nuts are also high in antioxidants.
(2018). A Pecan-Rich Diet Improves Cardiometabolic Risk Factors in Overweight and Obese Adults: A Randomized Controlled Trial.
Nutrients. 10(3), 339.
Link between nut intake and inflammatory biomarkers
Data from 5,013 men and women participating in the Nurses' Health Study and Health Professionals Follow-up Study has revealed that higher nut intake (5 or more times per week) was associated with lower levels of inflammatory biomarkers (C-reactive protein (CRP) and Interleukin 6 (IL6)).
Research has also shown that nut consumption may be inversely related to body mass index (BMI), which is a strong determinant of inflammatory biomarkers, so it may be that the associations between nut intake and inflammatory markers are mediated in part through BMI.
(2016). Associations between nut consumption and inflammatory biomarkers.
The American Journal of Clinical Nutrition. 104(3), 722 - 728.
- Long-known to lower LDL cholesteral, a new study shows oats also impact other markers that may be better measures of cardiovascular risk for those with diabetes or metabolic syndrome.
- An experimental study shows that whole grain foods significantly lower blood pressure compared to eating the equivalent refined grain foods.
- A review of population studies shows that the more whole grains you eat, the lower your risk of cardiovascular disease.
Eating oats lowers cholesterol on 3 markers
It’s long been known that eating oats can lower cholesterol levels, but the research focus has been on the effect on LDL cholesterol. However, there is growing evidence that two other markers provide an even more accurate assessment of cardiovascular risk:
- non-HDL cholesterol (total cholesterol minus HDL cholesterol)
- apolipoprotein B (apoB) — a lipoprotein that carries LDL cholesterol through the blood.
This is especially true for people with metabolic syndrome and Type 2 diabetes, since they typically don't have elevated LDL cholesterol levels.
In light of this, it’s good to see a review and meta-analysis of 58 clinical trials has concluded that eating oat fibre can reduce all three markers.
The reason is thought to lie in beta-glucan, a viscous soluble fibre, for which oats are a rich source. Oat bran contains twice as much as oat meal.
The review found that overall, LDL cholesterol was reduced by 4.2%, non-HDL cholesterol by 4.8% and apoB by 2.3%.
Whole grain diet reduces cardiovascular disease risk
A study involving 33 overweight and obese adults who followed a whole grain diet for eight weeks and a refined grain diet during another eight week period, found that those on the whole grain diet saw a more than three-fold improvement in diastolic blood pressure compared to the refined grain diet.
This improvement equates to reducing the risk of death from heart disease by almost one-third, and the risk of death from a stroke by two-fifths.
Participants were under 50. Before age 50, an elevated diastolic blood pressure is associated with increased cardiovascular disease risk (diastolic is the bottom number, when you’re given a blood pressure reading).
Overall, there were substantial reductions in body weight, fat loss, systolic blood pressure, total cholesterol, and LDL cholesterol during both diet periods, but these differences were due to the people changing their normal dietary habits to carefully controlled diets. The order of diets was randomized, and there was a ten week period between them. The 33 participants included 6 men and 27 women.
The finding is supported by a meta-analysis of 45 different population studies that investigated whole grain intake in relation to risk of future illness or death due to specific causes. The review found that eating three more portions of whole grain foods a day was associated with a lower risk for all cardiovascular diseases and for dying of cancer, diabetes, and respiratory and infectious diseases. Three servings would be, say, two slices of whole-grain bread and one bowl of whole-grain cereal.
The benefits were dose-dependent, with the lowest risk found among those with the highest intake of whole-grain products: 7 to 7 ½ servings of whole grain products a day. This corresponds to 210-225 grams of whole grain products in fresh weight and about 70-75 grams of whole grains in dry weight.
Ho, H., Sievenpiper, J., Zurbau, A., Blanco Mejia, S., Jovanovski, E., Au-Yeung, F., . . . Vuksan, V. (2016). The effect of oat β-glucan on LDL-cholesterol, non-HDL-cholesterol and apoB for CVD risk reduction: A systematic review and meta-analysis of randomised-controlled trials. British Journal of Nutrition, 116(8), 1369-1382. doi:10.1017/S000711451600341X
Kirwan, J. P., Malin, S. K., Scelsi, A. R., Kullman, E. L., Navaneethan, S. D., Pagadala, M. R., … Ross, A. B. (2016). A Whole-Grain Diet Reduces Cardiovascular Risk Factors in Overweight and Obese Adults: A Randomized Controlled Trial. The Journal of Nutrition, 146(11), 2244–2251. https://doi.org/10.3945/jn.116.230508
Aune Dagfinn, Keum NaNa, Giovannucci Edward, Fadnes Lars T, Boffetta Paolo, Greenwood Darren C et al. Whole grain consumption and risk of cardiovascular disease, cancer, and all cause and cause specific mortality: systematic review and dose-response meta-analysis of prospective studies BMJ 2016; 353 :i2716 http://www.bmj.com/content/353/bmj.i2716
Data from 3,349 participants in the PREDIMED Study who were free of diabetes at baseline but at high cardiovascular risk, has found that those who consumed higher amounts of saturated fatty acids and animal fat had a twofold higher risk of developing type 2 diabetes over 4.5 years than those with a lower intake of saturated and animal fat. 266 participants developed diabetes during the period.
They also found that those who had a higher intake of legumes (lentils, chickpeas, beans and peas) had a 35% lower risk of developing type 2 diabetes compared to those eating the least amount. The main benefit came from lentils, with chickpeas running second. Those with a higher intake consumed at least 28.75 grams/day (equivalent to 3.35 servings/week).
There was also a positive benefit when half a serving per day of foods rich in protein or carbohydrates (such as eggs, bread, rice and baked potato) was replaced with a similar amount of legumes.
Legumes are rich in B vitamins, with beneficial minerals such as calcium, potassium and magnesium. They have long been thought to protect against type 2 diabetes.
Guasch-Ferré, M. et al. 2017. Total and subtypes of dietary fat intake and risk of type 2 diabetes mellitus in the Prevención con Dieta Mediterránea (PREDIMED) study. Total and subtypes of dietary fat intake and risk of type 2 diabetes mellitus in the Prevención con Dieta Mediterránea (PREDIMED) study Am J Clin Nutr 2017 105: 3 723-735; First published online February 15, 2017. doi:10.3945/ajcn.116.142034
Becerra-Tomás N, Díaz-López A, Rosique-Esteban N, Ros E, Buil-Cosiales P, Corella D, Estruch R, Fitó M, Serra-Majem Ll, Arós F, Lamuela-Raventós R.M, Fiol M, Santos-Lozano J.M, Diez-Espino J, Portoles O, Salas-Salvadó J, PREDIMED study investigators. "Legume consumption is inversely associated with type 2 diabetes incidence in adults: a prospective assessment from the PREDIMED study". Clinical Nutrition (2017). http://dx.doi.org/10.1016/j.clnu.2017.03.015.
A meta-analysis of 40 epidemiological studies from 1999 to 2016 has concluded that that people in the highest category of dietary magnesium consumption had a 10% lower risk of coronary heart disease, 12% lower risk of stroke and a 26% lower risk of type-2 diabetes compared to those in the lowest category. A dose–response analysis revealed that a 100 mg/day increase in dietary magnesium intake is significantly associated with a 7%, 22%, and 19% decrease in the risk of stroke, heart failure, and type 2 diabetes, respectively.
Magnesium-rich foods include spices, nuts, beans, cocoa, whole grains and green leafy vegetables.
Magnesium deficiency is relatively common, estimated to affect between 2.5% and 15% of the population. The recommended dietary allowance of magnesium is 350mg/day for an average male adult and 300mg/day for an average adult female, with an additional 150mg/day during pregnancy and lactation
Fudi Wang et al. 2016. Dietary magnesium intake and risk of cardiovascular disease, type 2 diabetes, and allcause mortality: A dose-response meta-analysis of prospective cohort studies. BMC Medicine, DOI: 10.1186/s12916-016-0742-z
A study involving 1,818 Hispanic Americans has confirmed that diabetes, whether controlled or not, is linked to worse measures of cardiac structure and function, and also shows that this happens very early in the development of diabetes.
Demmer, R. T., Allison, M. A., Cai, J., Kaplan, R. C., Desai, A. A., Hurwitz, B. E., … Rodriguez, C. J. (2016). Association of Impaired Glucose Regulation and Insulin Resistance With Cardiac Structure and Function. Circulation: Cardiovascular Imaging, 9(10), e005032. https://doi.org/10.1161/CIRCIMAGING.116.005032
A number of studies have pointed to a link between depression and type 2 diabetes, but a new study indicates that this is not as straightforward as it seemed. The large Canadian study involving 2,525 adults aged 40-69 has found that it is not depression alone that increases the risk of developing diabetes, but depression in conjunction with metabolic risk factors such as obesity, high blood pressure and unhealthy cholesterol levels,.
The study found that those with metabolic symptoms but not depression were around four times more likely to develop diabetes than normally healthy people, while those with both depression and metabolic risk factors were more than six times more likely to develop diabetes. The combined effect of depression and metabolic symptoms was greater than the sum of the individual effects. But those with depression alone had no more risk than normally healthy people.
There are probably two main causes for this effect. One is that, as evidence shows, people suffering from depression are less likely to adhere to medical advice aimed at tackling metabolic symptoms. This makes the metabolic symptoms worse, which can exacerbate the symptoms of depression, and so it goes, in a horrible negative cycle.
The second reason is that some forms of depression are associated with changes in the body's metabolic systems which can lead to weight gain, high blood pressure and problems with glucose metabolism. Some antidepressant medications can also cause weight gain.
Schmitz, N., Deschenes, S. S., Burns, R. J., Smith, K. J., Lesage, A., Strychar, I., … Wang, J. L. (2016). Depression and risk of type 2 diabetes: the potential role of metabolic factors. Mol Psychiatry. Retrieved from http://dx.doi.org/10.1038/mp.2016.7
A small, Israeli study involving 48 overweight and obese older adults with Type 2 diabetes (average age 59) has found that those who ate a large breakfast containing whey protein managed their diabetes better.
Participants in the study were randomly alloted to one of three diets that contained the same number of calories, and followed the pattern: large breakfast, medium-sized lunch and small dinner. They followed this diet for 23 months. The groups varied in the type of breakfast: primarily whey protein; other proteins such as eggs, soy and tuna; a meal high in carbohydrates or starch.
After 12 weeks, the group on whey protein lost the most weight: 7.6 kg (16.7 pounds), compared to 6.1 kg (13.4 pounds) for those on the other proteins, and 3.1 kg (6.8 pounds) for those in the carbohydrate group. Those on whey protein were also more satiated and less hungry throughout the day, with lower glucose spikes after meals compared to the other two diets, and their HbA1C also decreased more than with the other two diets.
Data from 8,452 participants in the population-based Rotterdam Study found that, over eight years, 1,100 (13%) developed prediabetes and 798 (9.4%) developed diabetes. The risk of progressing from prediabetes to diabetes was up to 40% higher for those with low thyroid function. Even among those whose thyroid function was in the normal range at first measurement, progression from prediabetes to diabetes was 1.4 times higher for those in the lowest third of thyroid function levels compared with the highest third.
The average age of the participants was 65.
For two years, 70 obese postmenopausal women with normal fasting plasma glucose levels ate either a Paleolithic-type diet or a “prudent” diet. The Paleolithic-type diet was based on lean meat, fish, eggs, vegetables, fruits, nuts and berries, with rapeseed, olive oils and avocado as additional fat sources. The diet excluded dairy products, cereals, added salt and refined fats and sugar. 30% of the calories were supposed to come from protein, 30% from carbohydrates, and 40% from fats with high unsaturated fatty acid content. The prudent control diet had a markedly different target: 15% in protein, 30% in fat, and 55% in carbohydrates.
Both groups took part in 12 group sessions led by a dietitian, and kept ongoing records of their food intake.
Both groups lost significant body weight and had significantly less abdominal obesity, but the women eating the Paleolithic-type diet also had significantly lower levels of specific fatty acids associated with insulin resistance, compared with those on the prudent control diet. Presumably this reflects the marked change in the types of fats eaten. At the end of the two years, the women eating the Paleolithic-type diet reported that their intake of saturated fatty acids decreased by 19%, while monounsaturated fatty acids increased by 47% and polyunsaturated fatty acids by 71%.
A Finnish study involving 2,189 healthy men aged 42-60 found that over 19 years, 417 men (19%) were diagnosed with type 2 diabetes. Those with high omega-6 polyunsaturated fatty acid concentrations in their blood were 46% less likely to develop diabetes. When analyzed, it turned out that this association depended on linoleic and arachidonic acid concentrations only; high serum gamma-linolenic and dihomo-γ-linolenic acid concentrations were linked to a higher risk.
The serum linoleic acid concentration is determined by the person's diet, and the main sources of linoleic acid are vegetable oils, nuts and seeds. Arachidonic acid is present in meat and eggs; however, the human body can also make arachidonic acid from linoleic acid.
Gamma-linolenic acid and dihomo-γ-linolenic acid are mainly formed in the human body from linoleic acid, but their concentrations in serum are very low.
Linoleic acid is the most common omega-6 fatty acid, and has been linked to a reduced risk of cardiovascular diseases as well as type 2 diabetes.
Teymoor Yary, Sari Voutilainen, Tomi-Pekka Tuomainen, Anu Ruusunen, Tarja Nurmi, Jyrki K Virtanen 2016. Serum n-6 polyunsaturated fatty acids, delta-5- and delta-6-desaturase activities and risk of incident type 2 diabetes in men: The Kuopio Ischaemic Heart Disease Risk Factor Study. American Journal of Clinical Nutrition, Published online March 24, 2016 http://ajcn.nutrition.org/content/early/2016/03/23/ajcn.115.128629.abstract
Frailty, manifesting in weight loss and malnutrition, leading to decreased hyperglycemia and normalization of blood glucose levels, may develop in older diabetics. This in turn leads to an increased risk of hypoglycemia. Current guidelines suggest relaxed glycemic control in diabetic, frail elderly patients.
A British study reviewing the impact of frailty on blood glucose level normalization has suggested not simply a more relaxed glycemic control in frail elderly with diabetes, but that complete withdrawal of hypoglycemic medications may be necessary. The researchers recommend that doctors regularly review medications taken in this vulnerable population “with consideration of gradual reduction or complete withdrawal when frailty and significant weight loss emerge”.
The review is available free to read here: http://www.future-science.com/doi/full/10.4155/fsoa-2015-0016.
Data from a five-year sleep study involving 161 Caucasian, 121 African American and 56 Chinese non-shift working women aged 48-58 has found that going to bed later, and having greater variability in bedtime, were associated with higher insulin resistance, and greater bedtime advance (going to bed earlier) was associated with higher body mass index (BMI).
Changes in bedtime, and later bedtimes, were partly due to shifts in bedtime at the weekend.
Diabetes risk increases in midlife women, and this finding suggests that irregular sleep schedules may be an important factor. Metabolic health was better in women who had more regular sleep schedules, including regular bedtimes across weekdays and weekends."
Taylor BJ, Matthews KA, Hasler BP, Roecklein KA, Kline CE, Buysse DJ, Kravitz HM, Tiani AG, Harlow SD, Hall MH. Bedtime variability and metabolic health in midlife women: the SWAN Sleep Study. SLEEP 2016;39(2):457–465.
A study has revealed that the immune system has a seasonal cycle, in which its activity is boosted during the winter and relaxes during the summer. While the winter increase in immune defences presumably helps us stave off infections, it also raises the risk of harmful inflammation, effectively lowering the threshold for heart attacks, stroke, diabetes and even some psychiatric conditions. This may explain why deaths from conditions ranging from heart attacks to diabetes and schizophrenia increase in winter.
The study used blood samples from more than 16,000 people living in both the northern and southern hemisphere
Dopico, X. C., Evangelou, M., Ferreira, R. C., Guo, H., Pekalski, M. L., Smyth, D. J., … Todd, J. A. (2015). Widespread seasonal gene expression reveals annual differences in human immunity and physiology. Nature Communications, 6, 7000. http://doi.org/10.1038/ncomms8000
Anecdotal and scientific evidence suggests curcumin, a compound found in turmeric, promotes health because it lowers inflammation. However, it is not absorbed well by the body. Most curcumin in food or supplements stays in the gastrointestinal tract, and any portion that's absorbed is metabolized quickly.
A new study thinks they've come up with a better and more effective way to deliver curcumin, and in so doing has demonstrated how it works. Curcumin powder was mixed with castor oil and polyethylene glycol, allowing it to dissolve and be more easily absorbed by the gut to enter the bloodstream and tissues.
When this was given to mice who had been injected with an extract that stimulates an immune reaction, a key protein that triggers an immune response was blocked. The mice given plain curcumin, on the other hand, showed the same protein actively triggering an immune response.
The emulsified curcumin also stopped recruitment of macrophages. Inflammation triggered by overactive macrophages has been linked to cardiovascular disease, disorders that accompany obesity, Crohn's disease, rheumatoid arthritis, inflammatory bowel disease, diabetes and lupus-related nephritis.
Telomeres are the protective caps at the ends of chromosomes that affect how quickly cells age. With age, they shorten, and as their structural integrity weakens, the cells age and die quicker. Telomere length thus is a biomarker of cellular age. Stress is also thought to shorten telomere length.
A year-long study that looked at the effects of three healthy behaviors in 239 post-menopausal, non-smoking women has found that women who engaged in lower levels of healthy behaviors showed a significantly greater telomere shortening for every major life stressor that occurred. However, stress didn't lead to greater shortening in those women who maintained active lifestyles, healthy diets, and good quality sleep.
Shorter telomeres have become associated with a broad range of aging-related diseases, including stroke, vascular dementia, cardiovascular disease, obesity, osteoporosis diabetes, and many forms of cancer.
Puterman, E., Lin, J., Krauss, J., Blackburn, E. H., & Epel, E. S. (2015). Determinants of telomere attrition over 1 year in healthy older women: stress and health behaviors matter. Molecular Psychiatry, 20(4), 529–535. http://doi.org/10.1038/mp.2014.70
One big issue for which there is as yet no clear answer, is the question of whether it's the intensity or the amount of exercise which is more important.
One study involving 300 obese adults aimed to test this in a 6-month trial comparing those who maintained their usual activity level, those who did a low amount (around 30 minutes) of low-intensity exercise, those who did a high amount (around an hour) of low-intensity exercise, and those who did around 40 minutes of high-intensity exercise. All had five exercise sessions every week.
After 24 weeks of this, all the exercise groups showed smaller mean waist circumference and greater mean weight loss, compared to the control group, but there was no difference between the exercise groups in these measures. However, only the high-high group had lower 2-hour glucose levels than the controls, and only the two groups who did a higher amount of exercise had better insulin sensitivity.
Ross R et al. Effects of exercise amount and intensity on abdominal obesity and glucose tolerance in obese adults: A randomized trial. Ann Intern Med 2015 Mar 3; 162:325. (http://dx.doi.org/10.7326/M14-1189)
Medical and genetic data from thousands of patients has enabled researchers to compare the similarity between patients with type 2 diabetes, revealing three distinctive clusters. These sub-types of type 2 diabetes are associated with different genetic variants, and have quite different health implications.
Subtype 1 patients were more likely to suffer from well-known diabetes problems with kidneys and eyes (diabetic nephropathy and diabetic retinopathy); subtype 2 was more likely to suffer from cancer and cardiovascular diseases; and subtype 3 was associated most strongly with cardiovascular diseases, neurological diseases, allergies, and HIV infections.
Li, L., Cheng, W.-Y., Glicksberg, B. S., Gottesman, O., Tamler, R., Chen, R., … Dudley, J. T. (2015). Identification of type 2 diabetes subgroups through topological analysis of patient similarity. Science Translational Medicine, 7(311), 311ra174-311ra174. http://doi.org/10.1126/scitranslmed.aaa9364
A very small study, involving eight healthy young men and women, has found that insulin sensitivity gets worse the longer you're awake during the night.
During the study, one group had just five hours of available sleep time each night for five nights before five nights with nine hours of available sleep time. The other group did the opposite, starting with nine hours of available sleep time, followed by five hours per night. Participants were allowed to eat whatever they wanted during the short-night testing period.
The simulated five-day workweek of five hours of sleep per night resulted in a 20% reduced oral and intravenous insulin sensitivity, and it took three consecutive nights of nine hours of available sleep time to restore oral insulin sensitivity to previous levels.
It's worth emphasizing that these were all young and very healthy people.
Eckel, R. H., Depner, C. M., Perreault, L., Markwald, R. R., Smith, M. R., McHill, A. W., … Wright, K. P. (2015). Morning Circadian Misalignment during Short Sleep Duration Impacts Insulin Sensitivity. Current Biology, 25(22), 3004–3010. http://doi.org/10.1016/j.cub.2015.10.011
Data from 4.1 million British adults who were free of diabetes and cardiovascular disease at the start of the study has found that those with high blood pressure were almost 60% more likely to develop type 2 diabetes.
The strength of the association declined with increasing body mass index and age.
The finding strengthens previous research indicating that you are more at risk of diabetes if you have had high blood pressure, a heart attack or a stroke.
Emdin CA, Anderson SG, Woodward M, Rahimi K. Usual Blood Pressure and Risk of New-Onset Diabetes: Evidence From 4.1 Million Adults and a Meta-Analysis of Prospective Studies. J Am Coll Cardiol. 2015;66(14):1552-1562. doi:10.1016/j.jacc.2015.07.059.
Newly available 2011-2012 data from the very large National Health and Nutrition Examination Survey (NHANES) has revealed that Asian Americans have the highest proportion of undiagnosed diabetes among all ethnic and racial subgroups studied, at 51%. Diabetes was also common in Asian Americans, at 21%. The ethnic group with the highest prevalence of diabetes was Hispanic-Americans, at nearly 23%, with 49% of that undiagnosed.
One major reason for the high rate of undiagnosed diabetes among Asian-Americans may be that this group seem to develop type 2 diabetes at a lower body mass index than expected. The American Diabetes Association recommends Asian Americans get tested for diabetes at a BMI of 23 or higher, a lower threshold than the general population.
About 1 in 5 non-Hispanic black adults had diabetes, with 37% undiagnosed. Non-Hispanic whites had the lowest prevalence at 11%, and the lowest proportion of undiagnosed, at just over 32%.
However, overall the prevalence of diabetes has risen among American adults: from nearly 10% in 1988 to over 12% in 2012.
Your risk of developing type 2 diabetes is about three times greater if someone in your immediate family (parent, sibling) has it. In a study looking at the effects of exercise on this group, it was found that men who have a family member with type 2 diabetes had to expend more energy than a control group, to achieve the same benefits.
The study involved 35 unfit, slightly overweight but completely healthy men aged 30-45 who, for seven months, exercised regularly at a fitness centre. Half of them had relatives with type 2 diabetes, and half did not. (It's perhaps worth noting that 50 men began the study, but didn't continue — these were roughly evenly divided between the two groups.) Three hour-long exercise sessions were available each week, and participants went to 39 sessions on average (the range was large though: 11-107).
Those with family members with diabetes tended to go to the gym more often (group average was 59% more sessions), and this may be due to their increased motivation.
It must be emphasized that both groups lost weight, reduced their waist size, increased their fitness, and showed similar improvements in gene expressions. So exercise was a good idea for both groups. However, statistical analysis indicates that the at-risk group had to do more exercise than the control group to achieve the same benefit. The findings support earlier findings that those with close relatives with type 2 diabetes show smaller physiological changes to exercise, compared to those without such familial links.
Ekman, C., Elgzyri, T., Ström, K., Almgren, P., Parikh, H., Nitert, M. D., … Hansson, O. (2015). Less pronounced response to exercise in healthy relatives to type 2 diabetic subjects compared with controls. Journal of Applied Physiology, 119(9), 953–960. http://doi.org/10.1152/japplphysiol.01067.2014
In a study involving 52 sedentary, overweight, middle-aged men and women (aged 45-65), both exercise and calorie restriction had positive — and equal — effects on insulin sensitivity, but a combination of both had twice as much benefit for glucoregulation as either single approach. All three programs were designed to achieve about the same amount of weight loss (6-8%).
The study also indicated that both exercise and calorie restriction improve regulation of glucose levels through weight loss, but also through mechanisms that are independent of weight loss.
What all this suggests is that, even if you're maintaining a healthy weight, how much you eat, and whether you exercise, are factors that have health implications.
Weiss, E. P., Albert, S. G., Reeds, D. N., Kress, K. S., Ezekiel, U. R., McDaniel, J. L., … Villareal, D. T. (2015). Calorie Restriction and Matched Weight Loss From Exercise: Independent and Additive Effects on Glucoregulation and the Incretin System in Overweight Women and Men. Diabetes Care, 38(7), 1253–1262. http://doi.org/10.2337/dc14-2913
Sleep apnea is common among overweight and obese individuals, and many people with prediabetes have untreated sleep apnea, although few of them are aware of it.
A study involving 39 middle-aged, overweight or obese volunteers with prediabetes and sleep apnea has found that those who received two weeks of CPAP treatment improved their blood sugar control and the ability of insulin to regulate their blood sugar, and also had lower blood pressure and lower levels of the stress hormone norepinephrine.
Two-thirds of the volunteers received continuous positive airway pressure (CPAP) for eight hours during the night; the other 13 received a placebo to be taken before bedtime. They were told the study would compare the two treatments. All participants slept in the sleep laboratory and were closely monitored.
Sushmita Pamidi, Kristen Wroblewski, Magdalena Stepien, Khalid Sharif-Sidi, Jennifer Kilkus, Harry Whitmore, and Esra Tasali "Eight Hours of Nightly Continuous Positive Airway Pressure Treatment of Obstructive Sleep Apnea Improves Glucose Metabolism in Patients with Prediabetes. A Randomized Controlled Trial", American Journal of Respiratory and Critical Care Medicine, Vol. 192, No. 1 (2015), pp. 96-105. doi: 10.1164/rccm.201408-1564OC
A very small Israeli study, involving eight men and 10 women aged 30-70 with type 2 diabetes, has found that a big breakfast and a small dinner helped control blood sugar levels through the day.
Patients were randomly assigned to follow either a “B diet”, in which breakfast contained 2946 kilojoules, lunch 2523 kj, and dinner 858kj, or a “D diet”, which involved a 858 kj breakfast, 2523 kj lunch, and 2946 kj dinner. In other words, the same total amount of calories, in the same foods, was eaten by both groups, and lunch was the same for both, but the 'breakfast' and 'dinner' meals swapped timing.
After six days on the diet, patients ate their meals on the 7th day at the lab, where glucose levels were repeatedly tested during the day. After a break of two weeks, each patient was put on the alternate diet, and the same procedure was followed.
It was found that blood glucose levels rose 23% less after the lunch preceded by a large breakfast.
Jakubowicz, D., Wainstein, J., Ahrén, B., Bar-Dayan, Y., Landau, Z., Rabinovitz, H. R., & Froy, O. (2015). High-energy breakfast with low-energy dinner decreases overall daily hyperglycaemia in type 2 diabetic patients: a randomised clinical trial. Diabetologia, 58(5), 912–919. http://doi.org/10.1007/s00125-015-3524-9
Mouse and human immune cells have demonstrated that a compound produced by the body when dieting or fasting (β-hydroxybutyrate — BHB) directly inhibits a protein, NLRP3, which is part of a complex set of proteins that drive the inflammatory response in several disorders, including autoimmune diseases, type 2 diabetes, Alzheimer's disease, atherosclerosis, and autoinflammatory disorders.
BHB is produced in response to fasting, high-intensity exercise, caloric restriction, or consumption of the low-carbohydrate ketogenic diet.
The finding helps explain why calorie restriction reduces inflammation.
Youm, Y.-H., Nguyen, K. Y., Grant, R. W., Goldberg, E. L., Bodogai, M., Kim, D., … Dixit, V. D. (2015). The ketone metabolite β-hydroxybutyrate blocks NLRP3 inflammasome-mediated inflammatory disease. Nature Medicine, 21(3), 263–269. http://doi.org/10.1038/nm.3804
Studies have found that low levels of magnesium increases the chance that you will develop type 2 diabetes, but a large study shows that this association is modified by genetic variations in magnesium-related ion channel genes. So, for example, among Hispanic American women with high magnesium intake, those with one particular variant had a 35% lower risk of developing type 2 diabetes.
The study involved 7,287 black women and 3,285 Hispanic women aged 50-79.
Chan, K. H. K., Chacko, S. A., Song, Y., Cho, M., Eaton, C. B., Wu, W.-C. H., & Liu, S. (2015). Genetic Variations in Magnesium-Related Ion Channels May Affect Diabetes Risk among African American and Hispanic American Women. The Journal of Nutrition, 145(3), 418–424. http://doi.org/10.3945/jn.114.203489
A review of studies investigating lifestyle interventions that can delay or prevent the onset of type 2 diabetes in people with prediabetes and focusing specifically on ones that looked at gender differences, found that both men and women benefited equally from the interventions. The review of 12 studies found that those who received lifestyle interventions (including diet and exercise) were 40% less likely to progress to type 2 diabetes after 1 year, and 37% less likely to progress after 3 years.
People involved in lifestyle interventions also experienced greater weight reductions, and greater reductions of fasting plasma glucose.
Glechner, A., Harreiter, J., Gartlehner, G., Rohleder, S., Kautzky, A., Tuomilehto, J., … Kautzky-Willer, A. (2014). Sex-specific differences in diabetes prevention: a systematic review and meta-analysis. Diabetologia, 58(2), 242–254. http://doi.org/10.1007/s00125-014-3439-x
A new class of lipids produced in human and mouse fat has been discovered, and these ones seem to be good for you. Following the discovery that diabetes-resistant mice had dramatically higher levels of these “fatty acid hydroxy fatty acids (FAHFAs)”, levels were found to be low in pre-diabetic humans. Moreover, when mice with the equivalent of type 2 diabetes were given this lipid, blood sugar levels dropped and insulin levels rose. FAHFAs also seem to reduce inflammation.
FAHFAS are found in low levels in a wide range of vegetables, fruits and other foods, as well as being (unlike omega-3 fatty acids) produced and broken down inside the body.
Yore, M. M., Syed, I., Moraes-Vieira, P. M., Zhang, T., Herman, M. A., Homan, E. A., … Kahn, B. B. (2014). Discovery of a Class of Endogenous Mammalian Lipids with Anti-Diabetic and Anti-inflammatory Effects. Cell, 159(2), 318–332. http://doi.org/10.1016/j.cell.2014.09.035
Using data from about 600 000 adults over 26 years, researchers have concluded that the lifetime risk of developing type 2 diabetes for the average American 20-year-old rose from 20% for men and 27% for women in 1985, to 40% for men and 39% for women in 2000. The largest increases were in Hispanic men and women, and non-Hispanic black women, for whom lifetime risk now exceeds 50%.
Gregg, E. W., Zhuo, X., Cheng, Y. J., Albright, A. L., Narayan, K. M. V., & Thompson, T. J. (2014). Trends in lifetime risk and years of life lost due to diabetes in the USA, 1985–2011: a modelling study. The Lancet Diabetes & Endocrinology, 2(11), 867–874. http://doi.org/10.1016/S2213-8587(14)70161-5
Data collected from more than 5,300 employed Germans aged 29-66 has revealed that, over 13 years, 291 developed type 2 diabetes. Those who were under a high level of pressure at work and also perceived themselves as having little control over their activities had about a 45% higher risk of developing type 2 diabetes than those subjected to less workplace stress.
Huth, C. et al. (2014), Job Strain as a Risk Factor for the Onset of Type 2 Diabetes Mellitus: Findings From the MONICA/KORA Augsburg Cohort Study, Psychosomatic Medicine, 10.1097/PSY.0000000000000084
Public Health England states categorically for first time that excess weight is biggest risk factor for type 2 diabetes. Some 90% of people with the disease are overweight.
But note that abdominal fat is a better indicator of your chances of getting it than BMI. Men who measure more than 102cm (40 inches) around the middle are five times more likely to be diagnosed with type 2 diabetes than men with a smaller waist, while women who measure more than 88cm (35 inches) are three times more likely to be diagnosed than others.
A review of 12 studies involving more than 225,000 people, of whom almost 15,000 had diabetes, has found that shift work carries a 9% higher risk of type 2 diabetes, especially in men and those with rotating shift patterns. Men, in fact, had a 37% greater risk of developing diabetes if they did shift work, while those who did rotating shifts had a 42% higher risk than those who worked a fixed shift pattern.
Gan, Y., Yang, C., Tong, X., Sun, H., Cong, Y., Yin, X., … Lu, Z. (2015). Shift work and diabetes mellitus: a meta-analysis of observational studies. Occupational and Environmental Medicine, 72(1), 72–78. http://doi.org/10.1136/oemed-2014-102150
Oregano and rosemary turn out to be packed with healthful compounds that may work in much the same way as prescription anti-diabetic medication in keeping their blood-sugar level in check. While greenhouse-grow herbs contained more polyphenols and flavonoids compared to the equivalent commercial dried herbs, commercial extracts of Greek oregano, Mexican oregano and rosemary were better inhibitors of the enzyme, required to reduce risk of type-2 diabetes.
Bower, A. M., Real Hernandez, L. M., Berhow, M. A., & de Mejia, E. G. (2014). Bioactive Compounds from Culinary Herbs Inhibit a Molecular Target for Type 2 Diabetes Management, Dipeptidyl Peptidase IV. Journal of Agricultural and Food Chemistry, 62(26), 6147–6158. http://doi.org/10.1021/jf500639f
A Canadian study comparing neighborhoods that varied in “walkability” found that people living in neighborhoods with greater walkability had an average 13% lower likelihood of developing type 2 diabetes over 10 years, compared to those living in less walkable neighborhoods. However, walkability was only protective in those who were younger and middle aged; those who were age 65 or older saw no benefit from living in a walkable neighborhood.
Over the ten years of the study, the incidence of diabetes fell 7% in the most walkable neighborhoods, but rose 6% in the least walkable neighborhoods. Similarly, the incidence of excess weight (being overweight or obese) fell by 9% in the most walkable neighborhoods and rose 13% in the least walkable neighborhoods.
People who lived in the most walkable neighborhoods were three times more likely to walk or bicycle and half as likely to drive as a means of transportation.
The study was presented at the American Diabetes Association's 74th Scientific Session.
A Canadian study involving 141 people with Type 2 diabetes, who ate either a low glycemic index diet that included bread made with canola oil, or a whole wheat diet known to reduce the risk of cardiovascular disease, found that those on the canola bread diet experienced both a reduction in blood glucose levels and a significant reduction in LDL, or "bad," cholesterol. Moreover, the canola bread diet seemed to have the most significant impact on people who needed help the most — those whose HbA1c test measuring blood glucose over the previous two or three months was highest.
On the other hand, those on the whole wheat diet seemed to have better blood flow after 12 weeks than those on the canola bread diet.
Jenkins, D. J. A., Kendall, C. W. C., Vuksan, V., Faulkner, D., Augustin, L. S. A., Mitchell, S., … Leiter, L. A. (2014). Effect of Lowering the Glycemic Load With Canola Oil on Glycemic Control and Cardiovascular Risk Factors: A Randomized Controlled Trial. Diabetes Care, 37(7), 1806–1814. http://doi.org/10.2337/dc13-2990
A trial in which 163 overweight adults with elevated blood pressure were given one of four complete diets that contained all their food for five weeks has found that a low glycemic diet did not improve insulin sensitivity, lipid levels or blood pressure. But it's important to note than all diets were based on a healthful DASH-type diet, varying only in their glycemic index and carbohydrate proportions.
So, the trial found that a healthy diet with low–glycemic index carbohydrate-containing foods didn't improve insulin sensitivity, HDL cholesterol levels, LDL cholesterol levels, or systolic blood pressure any more than the healthy diet with high–glycemic index foods It did reduce plasma triglyceride levels slightly more.
In fact, the low–glycemic index with high-carbohydrate diet was worse than the high–glycemic index, high-carbohydrate diet — decreasing insulin sensitivity and increasing LDL cholesterol and LDL apolipoprotein B levels. This finding was unexpected and inconsistent with other research. However, a meta-analysis of 28 trials found that lowering glycemic index did not affect HDL cholesterol or triglyceride levels and lowered LDL cholesterol level only if fiber content was also increased.
In line with the researchers' previous findings, the DASH diet had slightly better effects when its carbohydrate content was reduced. When the same calories were instead supplied by unsaturated fat and protein, triglycerides and VLDL levels were substantially lowered and diastolic blood pressure slightly lowered.
As in previous trials, all the DASH-type diets lowered blood pressure and LDL cholesterol levels.
Previous research has shown inconsistent results on whether low glycemic index helped people lose weight.
Sacks FM, Carey VJ, Anderson CM, et al. Effects of High vs Low Glycemic Index of Dietary Carbohydrate on Cardiovascular Disease Risk Factors and Insulin Sensitivity: The OmniCarb Randomized Clinical Trial. JAMA. 2014;312(23):2531-2541. doi:10.1001/jama.2014.16658.
Goff LM, Cowland DE, Hooper L, Frost GS. Low glycaemic index diets and blood lipids: a systematic review and meta-analysis of randomised controlled trials. Nutr Metab Cardiovasc Dis. 2013;23(1):1-10.
Data from a survey of 20,000 people across the UK has found that people who cycle, walk, or take public transport to work had a lower risk of being overweight than those who drove or took a taxi. People who walked to work were 40% less likely to have diabetes than those who drove and 17% less likely to have high blood pressure. Cyclists were around half as likely to have diabetes as drivers.
Analysis of insulin-producing cells has revealed that those with type 2 diabetes have epigenetic changes in approximately 800 genes, with altered gene expression in over 100 genes (many of them relating to insulin production).
Epigenetic changes occur as a result of factors including environment and lifestyle, and are reversible. A number of these changes were also found in place in healthy subjects as a result of age or high BMI, suggesting these changes could contribute to the development of the disease
A review of 19 studies involving over 162,000 people has found that adherence to the Mediterranean diet was associated with a 21% reduced risk of diabetes, with a greater effect (27%) for those at high risk for cardiovascular disease. The association was found in both European and non-European groups.
The research was presented at the American College of Cardiology's 63rd Annual Scientific Session.
A 25-year study of diet and aging in 76 rhesus monkeys shows a significant reduction in mortality and in age-associated diseases among those on calorie-restricted diets.
These findings contradict an earlier primate study, perhaps because the current study reduced the diet of the experimental group by 30% based on what the adults wanted to eat. In the earlier study, both experimental and control animals were given diets based on a standardized food intake chart — meaning that the controls may have been on a restricted diet too (an idea supported by their weight, which was at all times less than that of the controls in the current study). Moreover, the earlier study, although reported as showing calorie restriction is ineffective, had 4 of the 10 experimental group achieve the unusual age of 40+, as did 1 of the 10 controls.
The current study also saw diabetes occurring in the control group, who were allowed to eat what they wanted.
A 2-year trial involving 59 patients with type 2 diabetes has found that those on a low-carbohydrate diet showed lower levels of inflammation compared with those on a traditional low-fat diet. Weight loss was similar in both groups.
Preliminary studies have demonstrated that grape skin extract exerts a novel inhibitory activity on hyperglycemia and could be developed to aid in diabetes management.
A meta-analysis of six studies from around the world, involving 75,498 couples, has found that a spouse had a 26% greater risk of developing diabetes if the other had been diagnosed with type 2 diabetes.
DNA data from more than 48,000 patients and 139,000 healthy controls from four different ethnic groups has identified seven new genetic regions associated with type 2 diabetes.
It is now realized that the focus in treating diabetes shouldn’t be so much on controlling blood sugar. New medical guidelines point to the importance of the following interventions (in order of benefit):
- smoking cessation (most important)
- blood pressure control
- metformin drug therapy
- lipid reduction
- glycemic control (least important).
This isn’t to say that blood sugar isn’t important; but the others should be dealt with first.
A study involving 614 patients with type 2 diabetes (mean age 62) has found that longer duration of diabetes was associated with more brain volume loss, particularly in the gray matter. Roughly, for every 10 years of diabetes, the brain was similar to that of a non-diabetic person who was two years older.
However, the study did not confirm any association of diabetes characteristics with small vessel ischemic disease.
Type 2 diabetes greatly increases a person's risk of developing cardiovascular disease, but a new study shows that cardiovascular risk factors such as elevated blood pressure and cholesterol levels differ significantly between men and women with diabetes.
The study, involving 680 diabetics, found that blood pressure and LDL cholesterol levels were significantly higher in women, and women were significantly less likely to have these factors under control. Some 17% of men had control of these factors, compared to 6% of women.
The findings suggest that more effort should be put into informing women about cardiovascular risk factors and how to reduce them.
Journal article freely available at http://online.liebertpub.com/doi/full/10.1089/dia.2013.0329