Does vitamin C supplementation exert profitable effects on serum lipid profile in patients with type 2 diabetes? A systematic review and dose-response meta-analysis.

Previous studies have reported that vitamin C supplementation may decrease lipid profile in patients with type 2 diabetes mellitus (T2DM). This systematic review and meta-analysis evaluated the influence of vitamin C supplementation on lipid profile in patients with T2DM. Studies examining the effects of vitamin C supplementation on lipid profile in patients with T2DM, published up to November 2020, were identified through PubMed, SCOPUS, and Embase databases. 15 studies, including 872 participants, were included and analyzed using a random-effects model to calculate weighted mean differences (WMDs) with 95% confidence intervals (CI). Findings from 15 studies indicated that vitamin C supplementation significantly decreased Triglyceride (TG) (WMD: -16.48 mg/dl, 95% CI (-31.89, -1.08), P < 0.001) and total cholesterol (TC) (WMD: -13.00 mg/dl, 95% CI (-23.10, -2.91), P < 0.001) in patients with T2DM. However, vitamin C supplementation failed to improve LDL and HDL. The meta-regression analysis suggested that lipid profile improvement was affected by duration of vitamin C treatment. Dose-response analysis showed that vitamin C supplementation changed LDL significantly based on vitamin C dose. According to our findings, vitamin C supplementation significantly improved lipid profile via decreases in TG and TC. However, vitamin C failed to affect LDL and HDL in diabetic populations. It appears that vitamin C supplementation is more beneficial to lipid profile in long-term vs. short term interventions.