Vitamin D supplementation has no effect on insulin sensitivity or secretion in vitamin D-deficient, overweight or obese adults: a randomized placebo-controlled trial.

Study answer

What this study found

Vitamin D supplementation increased 25(OH)D but did not improve insulin sensitivity or insulin secretion versus placebo after 16 weeks. 25(OH)D rose by 57.0 6 21.3 nmol/L in the vitamin D group versus 1.9 6 15.1 nmol/L with placebo (P = 0.02). Change in insulin sensitivity was essentially null for the M value: 0.02 6 2.0 mg -> kg 21 -> min 21 with vitamin D versus -0.03 6 2.8 mg -> kg 21 -> min 21 with placebo (P = 0.9). Total insulin AUC change was also not different: -21 6 212 mU/L versus -4 6 184 mU/L (P = 0.9), and there were no between-group differences in first-phase or second-phase…

Study & population

Randomized, placebo-controlled trial in otherwise healthy, non-diabetic adults aged 18 to 60 years with vitamin D deficiency and overweight or obesity (BMI at least 25 kg/m2).

Intervention

Oral cholecalciferol was given as a 100,000 IU bolus in 2 capsules, followed by 4,000 IU daily in 4 capsules for 16 weeks.

Key limitation

The analyzed sample was modest after attrition, with 28 vitamin D and 26 placebo participants, limiting power for smaller effects.

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Original abstract