Effects of Calcium Plus Vitamin D Supplementation on Anthropometric Measurements and Blood Pressure in Vitamin D Insufficient People with Type 2 Diabetes: A Randomized Controlled Clinical Trial

Background: Up to 75% of the risk of type 2 diabetes is attributable to obesity. Therefore, finding a way to control obesity can be useful for management of diabetes. Objective: This study was performed to assess the effects of vitamin D3 and calcium supplementation on anthropometric measurements and blood pressure in vitamin D insufficient people with type 2 diabetes. Methods: One hundred eighteen patients with diabetes were enrolled in this randomized placebo-controlled clinical trial. All subjects were randomly assigned into 4 groups receiving (1) 50,000 IU/wk vitamin D3 plus (equal to 7143 IU/d) calcium placebo; (2) 1000 mg/d calcium plus vitamin D3 placebo; (3) 50,000 IU/wk vitamin D3 (equal to 7143 IU/d) plus 1000 mg/d calcium; or (4) vitamin D3 placebo plus calcium placebo for 8 weeks. Anthropometric measurements and blood pressure were assessed at study baseline and after 8 weeks of intervention. Results: A greater reduction in body mass index was observed in calcium plus vitamin D group than other groups (p = 0.03). Comparison of changes in waist circumference among 4 groups revealed no significant difference in crude model (p = 0.21) and when the effect of confounders was taken into account (p = 0.08). Calcium supplementation resulted in a significant reduction in hip circumference compared to other groups (p <0.001). Systolic blood pressure significantly decreased in the calcium plus vitamin D group compared to placebo (−7.3 ± 8.7 mmHg vs 0.5 ± 8.2 mmHg; p = 0.001). However, calcium and vitamin D supplementation had no significant effects on diastolic blood pressure. Conclusion: Calcium–vitamin D3 cosupplementation can have beneficial effect on body mass index (BMI), hip circumference, and systolic blood pressure in vitamin D–insufficient type 2 diabetics.