Diabetes

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.

http://www.eurekalert.org/pub_releases/2016-03/uoef-hso032416.php

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

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."

http://www.eurekalert.org/pub_releases/2016-02/aaos-sli020116.php

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 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.

http://www.eurekalert.org/pub_releases/2015-11/uoca-los_1110415.php

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

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.

http://www.fastcoexist.com/3052935/the-latest-breakthrough-in-understanding-diabetes-was-made-by-an-algorithm

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

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.

http://www.eurekalert.org/pub_releases/2015-10/lu-eig100215.php

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

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.

http://www.eurekalert.org/pub_releases/2015-09/niod-mth090315.php

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.

http://www.theguardian.com/society/2015/sep/29/study-gives-strongest-link-yet-between-blood-pressure-and-diabetes

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.

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

http://www.theguardian.com/science/2015/may/12/winter-immune-boost-may-actually-cause-deaths-study-suggests

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

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.

http://www.eurekalert.org/pub_releases/2015-05/slu-ido050615.php

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.

http://www.eurekalert.org/pub_releases/2015-04/uocm-esa042715.php

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