The effect of vitamin D supplementation on glucose metabolism in type 2 diabetes mellitus: A systematic review and meta-analysis of intervention studies

Clare J Lee; Geetha Iyer; Yang Liu; Rita R Kalyani; N'Dama Bamba; Colin B Ligon; Sanskriti Varma; Nestoras Mathioudakis

doi:10.1016/j.jdiacomp.2017.04.019

The effect of vitamin D supplementation on glucose metabolism in type 2 diabetes mellitus: A systematic review and meta-analysis of intervention studies

J Diabetes Complications. 2017 Jul;31(7):1115-1126. doi: 10.1016/j.jdiacomp.2017.04.019. Epub 2017 Apr 21.

Authors

Clare J Lee¹, Geetha Iyer², Yang Liu², Rita R Kalyani³, N'Dama Bamba⁴, Colin B Ligon⁵, Sanskriti Varma⁶, Nestoras Mathioudakis³

Affiliations

¹ Division of Endocrinology, Diabetes & Metabolism, The Johns Hopkins University, Baltimore, MD, USA. Electronic address: clee158@jhmi.edu.
² The Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
³ Division of Endocrinology, Diabetes & Metabolism, The Johns Hopkins University, Baltimore, MD, USA.
⁴ The Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA; Division of Infectious Diseases, The Johns Hopkins University, Baltimore, MD, USA; Welch Center for Prevention, Epidemiology and Clinical Research, Johns Hopkins University, Baltimore, MD, USA.
⁵ Division of Rheumatology, The Johns Hopkins University, Baltimore, MD, USA.
⁶ The Johns Hopkins University School of Medicine, Baltimore, MD, USA.

Abstract

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 (-2.33mg/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 (-7.64mg/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.

Keywords: Glucose metabolism; Randomized controlled trials; Systematic review; Type 2 diabetes; Vitamin D.

Publication types

Meta-Analysis
Review
Systematic Review

MeSH terms

Blood Glucose / analysis
Combined Modality Therapy
Diabetes Mellitus, Type 2 / complications
Diabetes Mellitus, Type 2 / diet therapy*
Diabetes Mellitus, Type 2 / drug therapy
Diabetes Mellitus, Type 2 / metabolism
Dietary Supplements*
Evidence-Based Medicine*
Glycated Hemoglobin / analysis
Humans
Hyperglycemia / prevention & control*
Hypoglycemia / prevention & control*
Hypoglycemic Agents / therapeutic use
Randomized Controlled Trials as Topic
Reproducibility of Results
Vitamin D / analogs & derivatives
Vitamin D / blood
Vitamin D / therapeutic use*
Vitamin D Deficiency / blood
Vitamin D Deficiency / complications
Vitamin D Deficiency / diet therapy

Substances

Blood Glucose
Glycated Hemoglobin A
Hypoglycemic Agents
hemoglobin A1c protein, human
Vitamin D
25-hydroxyvitamin D

Abstract

Publication types

MeSH terms

Substances

Grants and funding