Vitamin D protects against diabetes among people with healthy sleep patterns

Individuals with higher circulating vitamin D concentrations are better protected against type 2 diabetes (T2D), especially those with healthier sleep patterns, a study has found.

The study population included 350,211 diabetes-free individuals. Those with higher 25OHD levels were older, less likely to be current smokers, and more likely to be current drinkers and with lower body mass index. They also tended to have a healthy diet, more sun exposure time in the summer, higher physical activity levels, and healthy sleep scores.

The researchers used five sleep behaviours, including sleep duration, insomnia, snoring, chronotype, and daytime sleepiness, to generate overall sleep patterns, defined by healthy sleep scores.

Over a median follow-up of 8.1 years, 6,940 participants developed T2D. Multivariable Cox proportional hazards analysis revealed that serum 25OHD was inversely associated with the risk of incident T2D, and the higher the concentration, the greater the protective benefit (hazard ratio [HR] per 10 nmol/L increase, 0.88, 95 percent confidence interval [CI], 0.87–0.90).

The association was modified by overall sleep patterns (p=0.002), such that the reduction in T2D risk conferred by higher serum 25OHD concentrations was more pronounced among participants with healthier sleep patterns. Among the individual sleep behaviours, daytime sleepiness showed the strongest modification effect (p=0.0006).

Finally, the genetic variations of the sleep patterns did not modify the relation between 25OHD and T2D.

The present data may have implications for T2D prevention strategies. People who have low vitamin D levels may benefit from supplementation, particularly those with daytime sleepiness, according to the researchers.