Effectiveness of niacin supplementation for patients with type 2 diabetes: A meta-analysis of randomized controlled trials.

BACKGROUND: Lipid profiles and glycemic control play a critical role in subsequent atherosclerotic cardiovascular disease for patients with type 2 diabetes mellitus (T2DM). This study aimed to evaluate the effectiveness of niacin supplementation on lipid profiles and glycemic control for patients with T2DM. METHODS: The PubMed, Embase, and the Cochrane Library databases were searched to identify randomized controlled trials (RCTs) that investigated the effects of niacin supplementation for patients with T2DM throughout December 2019. The weighted mean differences (WMDs) with 95% confidence intervals (CIs) were applied to calculate the pooled effect estimates using a random-effects model. RESULTS: Eight RCTs comprised a total of 2110 patients with T2DM who were selected for final quantitative analysis. The patients' niacin supplementation was associated with lower levels of total cholesterol (WMD, -0.28; 95% CI, -0.44 to -0.12; P = .001), triglyceride (WMD, -0.37; 95% CI, -0.52 to -0.21; P < .001), and low-density lipoprotein (WMD, -0.42; 95% CI, -0.50 to -0.34; P < .001). Moreover, the level of high-density lipoprotein was significantly increased when niacin supplementation (WMD, 0.33; 95% CI, 0.21 to 0.44; P < .001) was provided. However, niacin supplementation produced no significant effects on plasma glucose (WMD, 0.18; 95% CI, -0.14 to 0.50; P = .275) and hemoglobin A1c (HbA1c) levels (WMD, 0.39; 95% CI, -0.15 to 0.94; P = .158). CONCLUSIONS: This study found that niacin supplementation could improve lipid profiles without affecting the glycemic levels for patients with T2DM. Additional large-scale RCTs should be conducted to evaluate the long-term effectiveness of niacin supplementation.