MANAGEMENT OF ENDOCRINE DISEASE: The effect of vitamin D supplementation on glycaemic control in patients with type 2 diabetes mellitus: a systematic review and meta-analysis

Abstract

Objective: Epidemiologic studies suggest that vitamin D status plays a role in glycaemic control in patients with type 2 diabetes. However, intervention studies yielded inconsistent results. The aim of this study is to systematically review the effect of vitamin D supplementation on glycaemic control in patients with type 2 diabetes. Methods: Systematic review and meta-analysis. We searched Medline, Embase and the Cochrane Library for RCTs examining the effect of vitamin D supplementation on glycaemic control in patients with type 2 diabetes. A random-effects model meta-analysis was performed to obtain a summarized outcome of vitamin D supplementation on HbA 1c , fasting glucose and homeostasis model assessment -insulin resistance (HOMA-IR). Results: Twenty-three RCTs were included in this systematic review representing a total of 1797 patients with type 2 diabetes. Mean (± s.d.) change in serum 25-hydroxyvitamin D varied from 1.8 ± 10.2 nmol/L to 80.1 ± 54.0 nmol/L. Nineteen studies included HbA 1c as outcome variable. Combining these studies no significant effect in change of HbA 1c was seen after vitamin D intervention compared with placebo. A significant effect of vitamin D supplementation was seen on fasting glucose in a subgroup of studies (n = 4) with a mean baseline HbA 1c ≥ 8% (64 mmol/mol) (standardized difference in means: 0.36; 95% CI: 0.12-0.61, P = 0.003). Conclusions: Current evidence of RCTs does not support short-term vitamin D supplementation in a heterogeneous population with type 2 diabetes. However, in patients with poorly controlled diabetes, a favourable effect of vitamin D is seen on fasting glucose.

Effect of Vitamin D Supplementation on Some Inflammatory Biomarkers in Type 2 Diabetes Mellitus Subjects: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

“…Recently, it has been shown that there is a relationship of supplementation with vitamin D and glycemic control in adults [35]. In our analysis, we have focused on the common evaluated inflammatory biomarkers that might help to describe the relationship between vitamin D and T2DM.…”

Acute Vitamin D3 Supplementation in Severe Obesity: Evaluation of Multimeric Adiponectin

“…Evidence collected in case-control and observational studies led to the hypothesis that cholecalciferol administration could improve glucose tolerance, pancreatic beta-cell function, insulin and C-peptide responses, as well as insulin sensitivity [6,7,8]. However, the possibility that vitamin D 3 supplementation may help to prevent the risk of T2DM has been challenged, and the ability of vitamin D 3 supplementation to improve fasting glucose, HbA 1c levels, or insulin resistance in patients with impaired glucose tolerance (IGT), gestational diabetes, or T2DM is openly debated [9]. …”

The Relationship between Vitamin D and Type 2 Diabetes Is Intriguing: Glimpses from the Spect-China Study

“…In pre-diabetes, Wagner et al [28] have found no effect of high-dose vitamin D supplementation on β-cell function, insulin sensitivity or glucose homeostasis. According to a newly performed meta-analysis including 23 randomized clinical trials, the supplementation of vitamin D in T2DM patients did not show a significant effect on HbA1c, FPG, and HOMA-IR [29]. Moreover, it was found that hyperglycemia induced OGlcNAcylation of VDR in THP1 cells and in human macrophages derived from monocytes in an experimental study, which may be a pathophysiological explanation on the resistance of vitamin D [30].…”