Home-based, multi-trigger, multicomponent interventions with an environmental focus are effective in improving overall quality of life and productivity in children and adolescents with asthma. The effectiveness of these interventions in adults is inconclusive due to the small number of studies and inconsistent results. Additional studies are needed to (1) evaluate the effectiveness of these interventions in adults and (2) determine the individual contributions of the various intervention components.

Aims We aimed to assess whether vitamin D supplementation improves glucose metabolism in adults with type 2 diabetes. Methods PubMed and Cochrane database were searched up to July 1st 2016 for randomized controlled trials that assessed the relationship between vitamin D supplementation and glucose metabolism (change in hemoglobin A1C (HbA1C) and fasting blood glucose (FBG)) among adults with type 2 diabetes. Results Twenty nine trials (3324 participants) were included in the systematic review. Among 22 studies included in the meta-analysis, 19 reported HbA1C, 16 reported FBG outcomes and 15 were deemed poor quality. There was a modest reduction in HbA1C (−0.32% [−0.53 to −0.10], I2 = 91.9%) compared to placebo after vitamin D supplementation but no effect on FBG (−2.33 mg/dl [−6.62 to 1.95], I2 = 59.2%). In studies achieving repletion of vitamin D deficiency (n = 7), there were greater mean reductions in HbA1C (−0.45%, [−1.09 to 0.20]) and FBG (−7.64 mg/dl [−16.25 to 0.97]) although not significant. Conclusions We found a modest reduction of HbA1C after vitamin D treatment in adults with type 2 diabetes albeit with substantial heterogeneity between studies and no difference in FBG. Larger studies are needed to further evaluate the glycemic effects of vitamin D treatment especially in patients with vitamin D deficiency.

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