Effect of Vitamin D supplementation on glycemic parameters and progression of prediabetes to diabetes: A 1-year, open-label randomized study

BACKGROUND: Whether Vitamin D supplementation in prediabetes subjects prevents the development of diabetes is a matter of debate, and the results are inconsistent. This open-label, randomized study in subjects with prediabetes evaluated the effect of 12 months of Vitamin D supplementation on glycemic parameters and progression of prediabetes to diabetes in an ethnically homogeneous Kashmiri population. MATERIALS AND METHODS: A total of 147 subjects were diagnosed as prediabetes out of which 137 subjects were randomized to receive in addition to standard lifestyle measures, either Vitamin D 60,000 IU weekly for 4 weeks and then 60,000 IU monthly (n = 69) or no Vitamin D (n = 68). Fasting plasma glucose (FPG), 2-h plasma glucose and A1C levels were estimated at 0, 6 and 12 months. Changes in FPG, 2-h plasma glucose, A1C level and the proportion of subjects developing diabetes were assessed among 129 subjects. RESULTS: At 12 months, A1C levels were significantly lesser (5.7% ± 0.4%) in the Vitamin D supplemented group when compared with non-Vitamin D supplemented (6.0% ± 0.3%). Similarly, FPG (97 ± 7) and 2-h plasma glucose (132 ± 16) were significantly less in Vitamin D supplemented group as compared with non-Vitamin D supplemented group (FPG = 116 ± 6 and 2-h plasma glucose = 157 ± 25) at 12 months. Nine out of 65 in non-Vitamin D supplemented and seven out of 64 in the Vitamin D supplemented group developed diabetes. CONCLUSIONS: Vitamin D supplementation in prediabetes subjects significantly lowered FPG, 2-h plasma glucose and A1C levels.