Poster Presentation Australian Diabetes Society and the Australian Diabetes Educators Association Annual Scientific Meeting 2017

POSTER DISCUSSION: Vitamin D supplementation improves chronic low-grade inflammation in patients with type 2 diabetes: a systematic review and meta-analysis of randomised controlled trials (#221)

Aya Mousa 1 , Negar Naderpoor 1 , Helena J Teede 1 , Robert Scragg 2 , Barbora de Courten 1
  1. Monash Centre for Health Research and Implementation, School of Public Health and Preventive Medicine, Monash University, Melbourne, VIC, Australia
  2. School of Population Health, The University of Auckland, Auckland, New Zealand

BACKGROUND: Chronic low-grade inflammation is common in obesity and related chronic conditions, including type 2 diabetes. Vitamin D is proposed to have anti-inflammatory properties; however the effect of vitamin D supplementation on inflammation in type 2 diabetes has not been established.

PURPOSE: To conduct a systematic review and meta-analysis of the effects of vitamin D supplementation on inflammatory markers in patients with type 2 diabetes, and to identify relevant knowledge gaps.

DATA SOURCES: Medline, CINAHL, EMBASE and All EBM were systematically searched from inception to 25-January-2017 for randomised controlled trials (RCTs) investigating the effects of vitamin D supplementation on inflammatory markers in type 2 diabetes.

STUDY SELECTION: Two independent reviewers screened full-text articles of RCTs (no date or language limits) of vitamin D supplementation (any form, route, duration, or co-supplementation) compared to placebo/usual care on inflammatory markers in patients with type 2 diabetes.

DATA EXTRACTION: Two independent reviewers extracted data and assessed quality using the grading of recommendations, assessment, development and evaluation (GRADE) approach.

DATA SYNTHESIS: Twenty-eight RCTs met inclusion criteria, and 20 had available data for pooling. In meta-analyses of 20 RCTs (n=1,270), vitamin D-supplemented groups had lower follow-up levels of C-reactive protein (standardized mean difference (SMD[95%CI]):-0.23 mg/L(-0.37,-0.09);p=0.002), tumour necrosis factor (SMD:-0.49 pg/ml(-0.84,-0.15);p=0.005), and erythrocyte sedimentation rate (SMD:-0.47 mm/hr(-0.89,-0.05);p=0.03), and higher levels of leptin (SMD:0.42 µg/L(0.04, 0.81);p=0.03) compared to control groups. No differences were observed for adiponectin, interleukin-6, or E-selectin. In meta-regression and subgroup analyses, results were not influenced by age, sex, BMI, diabetes duration, baseline vitamin D status, or supplementation dose or duration. There was no evidence of heterogeneity (I2=0-38%;Phet>0.1) or publication bias and most studies had low to moderate risk of bias.

CONCLUSIONS: This meta-analysis of RCTs provides level one evidence that vitamin D supplementation may improve chronic low-grade inflammation in patients with type 2 diabetes.