Effects of Vitamin D Supplementation on Prevention of Type 2 Diabetes in Patients With Prediabetes: A Systematic Review and Meta-analysis

Diabetes Care
Q1
Jun 2020
Citations:153
Influential Citations:9
Systematic Reviews / Meta-Analyses
93
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Enhanced Details

Methods
Adults (≥18 years) with prediabetes; eight randomized controlled trials (including some cluster- and quasi-randomized designs) comparing vitamin D supplementation vs placebo; multi-country settings; follow-up 6 months to 5 years; prediabetes definitions varied across studies; data collection followed PRISMA guidelines.
Intervention
Oral vitamin D regimens varied: cholecalciferol (Vitamin D3) delivered in daily, weekly, or monthly schedules (e.g., 4,000 IU/day; 20,000–60,000 IU/week; loading followed by maintenance such as 60,000 IU/week then monthly). Durations ranged from 6 months to 5 years. One trial used Eldecalcitol (0.75 mg/day). Some regimens included calcium as a co-supplement (e.g., 500 mg/day).
Results
Vitamin D supplementation reduced the risk of progressing to type 2 diabetes in adults with prediabetes (pooled RR 0.89; 95% CI 0.80–0.99). Benefit was stronger in nonobese individuals (BMI <30 kg/m2; RR 0.73; 95% CI 0.57–0.92). Reversion from prediabetes to normoglycemia was higher with vitamin D (RR 1.48; 95% CI 1.14–1.92). Authors note the overall effect may be limited to nonobese subjects and call for individual participant data meta-analyses to confirm findings.
Limitations
Definitions of prediabetes and new-onset diabetes varied across trials; baseline vitamin D status and BMI varied; dosing regimens and co-interventions (e.g., calcium) differed; some trials carried risk-of-bias concerns; follow-up durations ranged from 6 months to 5 years; long-term outcomes and generalizability require further study.

Abstract

BACKGROUND While observational studies have shown an association between vitamin D insufficiency and diabetes, it is unclear whether intervention with vitamin D supplements can lower the risk of type 2 diabetes mellitus (T2DM). PURPOSE To assess whet...