Vitamin D and Diabetes Mellitus: What Do We Know?

Diabetes mellitus, as a common metabolic disease, affects millions people’s health worldwide and its incidence is continuing to increase. It is important to find effective measures of prevention and/or intervention for the disease to reduce its impact on the risk for cardiovascular disease – the leading cause of mortality among patients with diabetes mellitus. Apart from its well-known “classic” effect in bone metabolism, vitamin D has received widespread attention for its potential role in the prevention of diabetes mellitus, in particular type 2 diabetes mellitus. A large number of studies have observed a reverse relationship between vitamin D levels and the risk of diabetes mellitus. The results from the studies aiming to reduce risk for diabetes mellitus with vitamin D supplements are mixed though no study reports worsening the disease pathologically after treatment. Most previous studies on the relationship between vitamin D and diabetes mellitus were orientated from the direction of the “non-classic” effect of vitamin D, but the emerging evidence indicates that its “classic” effect on bone metabolism can be the key to understand its risk association with diabetes mellitus.