Effects of vitamin D supplementation on glycemic control of children and adolescents with type 1 diabetes mellitus: a systematic review.

Objectives: To evaluate the effect of vitamin D supplementation on glycemic control in children and adolescents with T1DM.

Content: A systematic search was conducted of the Medline/PubMed, Web of Science, Embase, BVS/Lilacs, Cochrane Library, Scopus, Cinahl, Food Science, and FSTA databases. Two reviewers independently extracted article data and assessed quality.

Summary: A total of 1,613 eligible articles were retrieved, ten of which met the selection criteria: eight clinical trials, one retrospective cohort study, and one cross-sectional study. Regarding the cutoff points used to classify vitamin D status, most of the studies set deficiency at 25-hydroxyvitamin D <20 ng/mL, sufficiency at ≥30 ng/mL, and insufficiency as the interval between these values. Regarding intervention strategies, most used cholecalciferol for supplementation, but there was great variation in the dose and supplementation time. When evaluating the effect of vitamin D supplementation on HbA1c, a significant improvement in glycemic control was observed in 50% of the studies. However, only one of these studies was classified as being of positive methodological quality, with three having their quality classified as neutral and one as negative.

Outlook: There is yet no consistent evidence on the effect of vitamin D supplementation on glycemic control as an adjuvant in the treatment of children and adolescents with T1DM.