The effect of vitamin D supplementation on mental and functional health outcomes in African Americans with type 2 diabetes
Abstract
In patients with type 2 diabetes (T2DM), depression increases the risk of poor glycemic control and decreases adherence to medications, exercise, and diet. Studies have shown an inverse relationship between plasma vitamin D (VD) level and depression risk. However, there are few interventional trials of African Americans (AAs), a demographic with higher prevalence of diabetes, depression, and VD deficiency. This randomized controlled trial evaluated the efficacy of vitamin D3 supplementation [4000 vs. 600 international units (IU)/day] for one year on mental and functional health outcomes in 75 adult AAs with T2DM with serum 25-hydroxy vitamin D (25(OH)D) level 30 ng/mL by 6 months with a plateau thereafter. Vitamin D3 4000 IU/day in AAs with T2DM did not produce significant difference in mental and functional health scores compared to 600 IU/day. Post-hoc analysis of those with baseline VD deficiency [25(OH)D < 20 ng/mL] demonstrated trends towards worsening pain interference and higher depression and fatigue scores throughout the study, plus consistently shorter 6-minute walk distances, most of which were independent of vitamin D supplementation group. These results suggest that VD deficient AAs with T2DM may be refractory to supplementation for improvement in mental and functional health outcomes.
How strong is the evidence?
Evidence Hub reads this as a randomized trial, done in people. Its evidence level is 2 of 5 (High · randomized trial). Randomized trials of a reasonable size are the strongest single-study design.
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