Ethnicity Differences in the Association of UCP1‐3826A/G, UCP2‐866G/A and Ala55Val, and UCP3‐55C/T Polymorphisms with Type 2 Diabetes Mellitus Susceptibility: An Updated Meta‐Analysis

Background . The relationship between uncoupling protein (UCP) 1‐3 polymorphisms and susceptibility to type 2 diabetes mellitus (T2DM) has been extensively studied, while conclusions remain contradictory. Thus, we performed this meta‐analysis to elucidate whether the UCP1‐3826A/G, UCP2‐866G/A, Ala55Val, and UCP3‐55C/T polymorphisms are associated with T2DM. Methods . Eligible studies were searched from PubMed, Cochrane Library, and Web of Science database before 12 July 2020. Pooled odds ratios (ORs) with corresponding 95% confidence intervals (CIs) were calculated to evaluate the strength of the association. Heterogeneity analysis, subgroup analysis, sensitivity analysis, and publication bias were also performed. Results . A total of 38 case‐control studies were included in this meta‐analysis. The overall results revealed significant association between T2DM and the UCP2 Ala55Val polymorphism (recessive model: OR = 1.25, 95% CI 1.12‐1.40, P < 0.01; homozygous model: OR = 1.33, 95% CI 1.03‐1.72, P = 0.029, respectively). In subgroup analysis stratified by ethnicity, T2DM risk was increased with the UCP2 Ala55Val polymorphism (allele model: OR = 1.17, 95% CI 1.02‐1.34, P = 0.023; recessive model: OR = 1.28, 95% CI 1.13‐1.45, P < 0.01; homozygous model: OR = 1.39, 95% CI 1.05‐1.86, P = 0.023, respectively), while decreased with the UCP2‐866G/A polymorphism in Asians (dominant model: OR = 0.86, 95% CI 0.74‐1.00, P = 0.045). Conclusions . Our results demonstrate that the UCP2‐866G/A polymorphism is protective against T2DM, while the UCP2 Ala55Val polymorphism is susceptible to T2DM in Asians.