A randomized, placebo-controlled trial of vitamin D supplementation to improve glycaemia in overweight and obese African Americans
Diabetes, Obesity and Metabolism, 08/02/2012
Harris SS et al. – Supplementation with 4000 IU/day vitamin D3 successfully corrected vitamin D insufficiency and had divergent effects on insulin secretion and sensitivity with no overall effect on disposition index or glycaemia. In this study, vitamin D supplementation for 3 months did not change the pathophysiology of prediabetes in overweight and obese African Americans.Methods
- In this randomized, placebo–controlled trial, the authors examined the effect of 4000 IU/day vitamin D3, on glycaemia and contributing measures including insulin secretion, insulin sensitivity and the disposition index over 12 weeks in 89 overweight or obese African Americans with prediabetes or early diabetes.
- Outcome measures were derived from oral glucose tolerance testing.
- Mean plasma 25–hydroxyvitamin D was about 40 nmol/l in the placebo and vitamin D groups at baseline and increased to 81 nmol/l with supplementation.
- Insulin sensitivity decreased by 4% in the vitamin D group compared with a 12% increase in the placebo group (p = 0.034).
- Insulin secretion increased by 12% in the vitamin D group compared with a 2% increase in the placebo group (p = 0.024), but changes in the disposition index were similar across groups.
- There was no effect of supplementation on post–load glucose or other measures of glycaemia.