Effect of Vitamin D Supplementation on the Incidence of Diabetes Mellitus

Abstract

<jats:title>Abstract</jats:title> <jats:sec> <jats:title>Context</jats:title> <jats:p>The effect of vitamin D supplementation on the risk of type 2 diabetes mellitus (T2DM) remains controversial because most randomized controlled trials (RCTs) have been small or have reported low doses of vitamin D.</jats:p> </jats:sec> <jats:sec> <jats:title>Objective</jats:title> <jats:p>To conduct a meta-analysis of RCTs testing vitamin D supplementation in the prevention of T2DM.</jats:p> </jats:sec> <jats:sec> <jats:title>Data Sources</jats:title> <jats:p>Database search of PubMed/MEDLINE, EMBASE, and the Cochrane Library was performed by 2 reviewers from inception through September 15, 2019.</jats:p> </jats:sec> <jats:sec> <jats:title>Study Selection</jats:title> <jats:p>We included RCTs that reported the effect of vitamin D supplementation for at least 1 year on T2DM prevention.</jats:p> </jats:sec> <jats:sec> <jats:title>Data Extraction</jats:title> <jats:p>Two independent reviewers extracted the data. The risk ratios (RRs) and 95% confidence intervals (CIs) were reported. Primary outcome of the meta-analysis was the incidence of T2DM.</jats:p> </jats:sec> <jats:sec> <jats:title>Data Synthesis</jats:title> <jats:p>Nine RCTs were included (43 559 participants). The mean age (standard deviation) was 63.5 (6.7) years. The RR for vitamin D compared with placebo was 0.96 (95% CI, 0.90-1.03); P = 0.30. In trials testing moderate to high doses of supplementation (≥1000 IU/day), all conducted among participants with prediabetes, the RR for vitamin D compared with placebo was 0.88 (95% CI, 0.79-0.99). In contrast, the trials testing lower doses, which were conducted in general population samples, showed no risk reduction (RR, 1.02; 95% CI, 0.94-1.10; P, interaction by dose = 0.04).</jats:p> </jats:sec> <jats:sec> <jats:title>Conclusion</jats:title> <jats:p>In patients with prediabetes, vitamin D supplementation at moderate to high doses (≥1000 IU/day), significantly reduced the incidence risk of T2DM, compared with placebo.</jats:p> </jats:sec>

Vitamin D Supplementation for Prevention of Type 2 Diabetes Mellitus: To D or Not to D?

“…If vitamin D supplementation promotes regression to euglycemia, then more people will spend more time in the low-risk state away from prediabetes/diabetes. Therefore, the higher likelihood of reversal to euglycemia with vitamin D supplementation (~48% more likely, as stated by Zhang et al) may, by delaying time-to-onset of diabetes, represent an additional benefit to the 12% lower risk to progression to diabetes reported by the 2 meta-analyses of clinical trials ( 52 , 53 ).…”

“…Two trials not designed for diabetes prevention (total of 39 243 participants) were in persons of average diabetes risk randomized to low-dose vitamin D (<1000 IU per day); 7 trials (total of 4316 participants) designed for diabetes prevention were in persons with prediabetes randomized to high-dose vitamin D (≥1000 IU per day). The authors reported a significant benefit of vitamin D supplementation for incident diabetes only after combining data from the diabetes prevention trials among persons with prediabetes who also received high-dose vitamin D (risk ratio 0.88; 95% CI: 0.79–0.99; p = 0.043) ( 53 ).…”

Role of Vitamin D in the Metabolic Syndrome

“…In relation to IR, several studies have shown positive effects of vitamin D supplementation in pre-diabetic patients [ 48 , 49 ]. In their work, Lemieux et al demonstrated that supplementation with 5000 IU daily of vitamin D for 6 months increased insulin sensitivity and pancreatic β-cell activity [ 48 ].…”

Response to Letter to the Editor from Dalan: “Vitamin D Supplementation for Prevention of Type 2 Diabetes Mellitus: To D or Not to D?”

“…We thank Rinkoo Dalan for the comments on our paper ( 1 , 2 ). We agree that although the reduction in diabetes risk with vitamin D supplementation among people at high risk for diabetes appears to be moderate (~ 12% relative risk reduction compared to placebo) ( 3 ), certain individuals may derive a higher (or lower) benefit based on certain characteristics. For example, in the simplest demonstration of such heterogeneity, vitamin D supplementation reduced diabetes risk by 62% among participants in the Vitamin D and Type 2 Diabetes (D2d) study who had a baseline serum 25-hydroxyvitamin D (25[OH]D) level of less than 12 ng/mL (30 mmol/L) ( 2 ).…”