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Effect of vitamin D supplementation on insulin resistance and glycaemic control in prediabetes: a systematic review and meta‐analysis
Author(s) -
Poolsup N.,
Suksomboon N.,
Plordplong N.
Publication year - 2016
Publication title -
diabetic medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.474
H-Index - 145
eISSN - 1464-5491
pISSN - 0742-3071
DOI - 10.1111/dme.12893
Subject(s) - medicine , insulin resistance , prediabetes , homeostatic model assessment , insulin , randomized controlled trial , endocrinology , vitamin d and neurology , glucose tolerance test , cochrane library , homeostasis , subgroup analysis , vitamin , meta analysis , gastroenterology , diabetes mellitus , type 2 diabetes
Aims To evaluate the effect of vitamin D on insulin resistance and glycaemic control in prediabetes. Methods A literature search was conducted of MEDLINE , the Cochrane Library, Cumulative Index to Nursing and Allied Health Literature ( CINAHL ), Scopus, Web of Science and www.clinicaltrials.gov , together with a historical search through the reference lists of relevant articles until end of June 2014. Studies were included if they were randomized controlled trials of vitamin D or vitamin D analogues in prediabetes and if they reported homeostatic model assessment of insulin resistance or 2‐h plasma glucose after oral glucose tolerance test. Treatment effect was estimated according to mean difference in the changes from baseline of homeostatic model assessment of insulin resistance, 2‐h oral glucose tolerance test plasma glucose, fasting plasma glucose and HbA 1c between vitamin D and control groups. Meta‐analysis of eligible studies was performed. Results A total of 10 randomized controlled trials were included. Vitamin D did not significantly improve homeostatic model assessment of insulin resistance and 2‐h oral glucose tolerance test plasma glucose: the mean differences were ‐0.06 (95% CI ‐0.36 to 0.24) and ‐0.23 mmol/l (95% CI ‐0.65 to 0.19), respectively. Subgroup analysis suggested that vitamin D improved homeostatic model assessment of insulin resistance in a subgroup with baseline 25‐hydroxyvitamin D ≥ 50 nmol/l [mean difference ‐0.59 (95% CI ‐1.14 to ‐0.04); P = 0.03] and improved 2‐h oral glucose tolerance test plasma glucose in the subgroup with baseline 25‐hydroxyvitamin D < 50 nmol/l [mean difference ‐0.68 mmol/l (95% CI ‐1.35 to ‐0.01); P = 0.05]. Vitamin D significantly reduced fasting plasma glucose and HbA 1c levels. The mean differences were ‐0.10 mmol/l (95% CI ‐0.18 to ‐0.03), P = 0.006 and ‐1 mmol/mol (95% CI ‐2 to 0), P = 0.008, respectively. Conclusions No beneficial effect of vitamin D in improving insulin resistance was identified.