Bruna-Mejías, AlejandroValdivia-Arroyo, RocíoBecerra-Rodríguez, Emelyn SofíaClasing-Cárdenas, IgnacioCastaño-Gallego, Yesica TatianaGranite, GuinevereOrellana-Donoso, MathiasOyanedel-Amaro, GustavoNova-Baeza, PabloCifuentes-Suazo, GloriaSuazo Santibañez, AlejandraSanchis-Gimeno, JuanGutiérrez Espinoza, HéctorValenzuela Fuenzalida, Juan José2025-09-302025-09-302025-09-18Nutrients, Vol. 17, N°18, 2991 (2025) p. 1-38.2072-6643https://hdl.handle.net/20.500.12254/4328Background and Aims: Numerous clinical and observational studies have examined the role of vitamin D in glycemic control and metabolic regulation among diabetic patients, but findings remain inconsistent. This meta-analysis aimed to assess the effects of vitamin D supplementation on glycosylated hemoglobin (HbA1c%), HOMA-IR, HOMA-β, LDL cholesterol, total cholesterol, triglycerides, fasting insulin, fasting plasma glucose, C-reactive protein, and the likelihood of reversion to normoglycemia in prediabetic individuals. Methods: A comprehensive search of multiple databases was performed using keywords including “diabetes mellitus,” “type 2 diabetes,” “vitamin D supplementation,” and “VD supplementation.” Twenty studies met the inclusion criteria. Results: Vitamin D supplementation was associated with significant improvements across several parameters, including HOMA-β (SMD = 0.71; 95% CI: 0.63–0.80; p < 0.00001), HDL cholesterol (SMD = 0.07; 95% CI: 0.05–0.09; p < 0.00001), and others (SMD = −0.40; 95% CI: −0.45 to −0.34; p < 0.00001). Conclusions: Vitamin D supplementation appears to provide beneficial effects on glycemic, lipid, and inflammatory markers in patients with diabetes and prediabetes. Specifically, supplementation significantly reduced HbA1c%, HOMA-IR, LDL cholesterol, total cholesterol, triglycerides, fasting insulin, fasting glucose, and C-reactive protein while increasing the rate of normoglycemia among prediabetic individuals. Further research is needed to strengthen the evidence base regarding vitamin D’s role in diabetes management.enAtribución-NoComercial-CompartirIgual 3.0 Chile (CC BY-NC-SA 3.0 CL)Vitamin D supplementationVitamin DDiabetes mellitus type 1Diabetes type 2Articlehttps://orcid.org/0000-0002-1781-062Xhttps://doi.org/10.3390/nu17182991