Diabetes Prevention: Vitamin D Supplementation May Not Provide Any Protection If There Is No Evidence of Deficiency!

Nutrients. 2019 Nov 4;11(11):2651. doi: 10.3390/nu11112651.


The results of epidemiological and several interventional studies suggest an association between vitamin D deficiency and an increased risk of developing insulin resistance or type 2 diabetes. Various studies have indicated that a lack of vitamin D must be regarded as a pathogenic factor for type 2 diabetes and the metabolic syndrome, since a vitamin D deficiency (25(OH)D < 20 ng/mL) increases insulin resistance and reduces insulin secretion from beta cells in the pancreas. A recent study by Pittas et al. did not show a clear preventive effect of vitamin D supplementation with respect to the risk of developing type 2 diabetes. In terms of this study, it must be remembered that more than 70% of the participants in both the vitamin D supplement group and the placebo group did not have a vitamin D deficiency. In medical and pharmaceutical practice, more attention should be paid to vitamin D deficiency than has previously been accorded. Vitamin D status can be assessed objectively when necessary by laboratory testing of the serum 25(OH)D levels. Type 2 diabetes patients benefit from improving their vitamin D status with respect to their glucose metabolism and decreased mortality risk. Patients with insulin resistance who are vitamin D deficient should be treated with an appropriate amount of vitamin D to achieve circulating levels of 25(OH)D of 40-60 ng/mL.

Keywords: 25-hydroxyvitamin D; glucose metabolism; insulin resistance; prediabetes; type 2 diabetes; vitamin D.

MeSH terms

  • Blood Glucose
  • Diabetes Mellitus, Type 2 / drug therapy*
  • Diabetes Mellitus, Type 2 / prevention & control
  • Glucose / metabolism
  • Humans
  • Obesity
  • Vitamin D / administration & dosage*
  • Vitamin D / pharmacology
  • Vitamin D Deficiency*


  • Blood Glucose
  • Vitamin D
  • Glucose