Association Between Serum Vitamin D Levels and Insulin Resistance in Women With Polycystic Ovary Syndrome: A Systematic Review and Meta‐Analysis

BACKGROUND: Vitamin D deficiency has been proposed as a potential contributor to insulin resistance (IR) in polycystic ovary syndrome (PCOS); however, the evidence remains inconclusive. This meta-analysis evaluated the association between serum 25-hydroxyvitamin D [25(OH)D] and IR in PCOS. METHODS: We systematically searched PubMed, Embase, Web of Science, and Cochrane Library up to December 2025 for observational studies reporting correlations of 25(OH)D with IR indices (HOMA-IR/fasting insulin) in women with PCOS. Pooled correlation coefficients (r) with 95% confidence intervals (CI) were calculated using random-effects models. RESULTS: = 58%). Subgroup analyses revealed stronger associations in overweight/obese women (r = -0.35) and in Asian populations (r = -0.36). Women with vitamin D deficiency (< 20 ng/mL) showed a stronger correlation (r = -0.38). Sensitivity analysis confirmed robustness, and no significant publication bias was detected. CONCLUSION: Lower serum vitamin D is significantly associated with greater insulin resistance in PCOS, especially in overweight/obese and Asian subgroups. These findings highlight the potential value of assessing vitamin D status in the metabolic evaluation of PCOS.