ABSTRACT
Objective To systematically review the evidence for the effect of vitamin D supplementation on insulin resistance and blood glucose in people who are obese or people with abnormal glucose metabolism. Methods We searched databases including Pubmed, Elsevier, Web of Science, and WANFANG Database etc. for randomized controlled trials comparing vitamin D or analogues with placebo. We extracted data on insulin resistance and blood glucose, including homeostasis model assessment of insulin resistance( HOMA-IR), fasting blood glucose, HbA1C (% ). A1l data were analyzed using Review Manager 5. 0. Results Nine studies involving 867 participants were included. The results of meta-analysis showed that: ( 1 ) For people who are obese and with abnormal glucose metabolism, meta-analysis showed a small improvement in HOMA-IR(SMD -0. 34,95% CI -0. 61 to -0. 06, P<0. 05) and a small effect on fasting glucose (SMD -0. 41 mmol/ L, 95% CI -0. 68 to -0. 15, P<0. 05),while such effects were not seen in people who are obese but with normal blood glucose. (2) No serious adverse events were associated with the administration of vitamin D. Conclusion vitamin D supplementation may be benefit for improving insulin resistance and fasting blood glucose in people who are obese and with abnormal glucose metabolism, but has no effect on obese people with normal blood glucose.