Scientists from Peking University report that higher vitamin D levels in the body are associated with a lower risk of developing type 2 diabetes.
Type 2 diabetes is the most common form of diabetes. It occurs when blood glucose — also known as blood sugar — becomes too high. Glucose is the body’s main source of energy and comes primarily from food.
Insulin, a hormone produced by the pancreas, helps glucose enter cells to be used for energy. In type 2 diabetes, the body either does not produce enough insulin or does not use it effectively. As a result, glucose builds up in the bloodstream instead of entering the cells.
Fortunately, lifestyle changes can help prevent or delay the onset of type 2 diabetes.
Vitamin D functions like a hormone in the body. It is produced in the skin after exposure to sunlight and then activated by the liver and kidneys. The active form helps regulate calcium metabolism and supports many other bodily functions.
Previous studies have suggested a link between vitamin D levels and type 2 diabetes risk, but the findings have been inconsistent. Emerging evidence also indicates that vitamin D metabolism may be connected to sleep behaviors.
In the current study, researchers examined the relationship between vitamin D levels — measured as serum 25-hydroxyvitamin D (25OHD) — and the risk of type 2 diabetes, as well as whether sleep patterns influence this association.
The team analyzed data from more than 350,000 participants in the UK Biobank who did not have diabetes at the start of the study. Blood vitamin D levels were measured, and five sleep behaviors were assessed: sleep duration, insomnia, snoring, chronotype (morning or evening preference), and daytime sleepiness. Researchers also calculated genetic risk scores related to sleep patterns.
Over an average follow-up of eight years, 6,940 participants developed type 2 diabetes.
The researchers found that higher vitamin D levels were strongly associated with a lower risk of developing type 2 diabetes.
They also observed a significant interaction between vitamin D levels and overall sleep patterns. Among individuals with healthier sleep habits, higher vitamin D levels were linked to an even lower risk of diabetes.
Of the sleep factors examined, daytime sleepiness showed the strongest influence. People who did not frequently feel sleepy during the day appeared to gain greater protective benefits from higher vitamin D levels than those with excessive daytime sleepiness.
Genetic differences related to sleep patterns did not significantly alter the relationship between vitamin D levels and diabetes risk.
Overall, the findings suggest that higher vitamin D levels are associated with a reduced risk of type 2 diabetes, and that healthy sleep habits — particularly avoiding excessive daytime sleepiness — may strengthen this protective effect.
The study was conducted by Mengying Wang and colleagues and published in the journal Diabetes Care.
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