Taking high-dose vitamin D supplements for five years fails to impact incidence of type 2 diabetes: Study

Using significantly higher doses of vitamin D than recommended for five years did not affect the incidence of type 2 diabetes in elderly men and women, according to a new study from the University of Eastern Finland.

In population studies, low levels of vitamin D in the body have been associated with a higher risk of type 2 diabetes. However, such observational studies cannot directly conclude whether using vitamin D supplements can reduce the risk of developing the disease. Experimental studies have shown that the use of significantly higher doses of vitamin D than recommended slightly reduces the risk of developing type 2 diabetes in individuals with impaired glucose metabolism, i.e., those with prediabetes. In contrast, no effects have been observed in individuals without prediabetes. However, the studies with non-prediabetic subjects have used relatively small doses of vitamin D or have been short-term. Until now, there has been no research data on the effects of long-term use of high doses of vitamin D on the risk of type 2 diabetes in individuals without glucose metabolism disorders.

In the Finnish Vitamin D Trial (FIND) conducted at the University of Eastern Finland from 2012 to 2018, 2,495 men aged 60 and older and women aged 65 and older were randomised for five years into either a placebo group or groups receiving either 40 or 80 micrograms of vitamin D3 per day. In the statistical analyses of the now-published sub-study, 224 participants who were already using diabetes medications at the start of the study were excluded. Comprehensive information was collected from the participants on lifestyle, nutrition, diseases, and their risk factors. Data was also obtained from national health registers. About one-fifth were randomly selected for more detailed examinations, and blood samples were taken from them.