The association between urinary cadmium and diabetes risk remains controversial. PubMed, Web of Science, China National Knowledge Infrastructure, and Wanfang Data updated on 21 June 2016 were searched for eligible publications. Pooled odds ratio (OR) with 95% confidence interval (CI) of diabetes for highest versus lowest level of urinary cadmium was calculated by using fixed-effect model or random-effect model. Dose-response relationship between urinary cadmium and diabetes was estimated by restricted cubic spline. A total of nine studies with 28,691 participants were included in this meta-analysis. The pooled OR of diabetes for the highest versus lowest level of urinary cadmium was 1.02 (95% CI, 1.00, 1.05; I 2 = 42.3%). In subgroup analysis, the ORs were 1.02 (95% CI 1.00, 1.05; I 2 = 0.9%) for studies conducted in Asia and 1.11 (95% CI 0.88, 1.41; I 2 = 86.3%) in America. For dose-response analysis, a linear relationship was found between urinary cadmium and the risk of diabetes (P for nonlinear = 0.5856). For every l μg/g creatinine increment of urinary cadmium, the risk of diabetes increased by 16% (1.16, 95% CI 1.08, 1.25). This meta-analysis suggests that cadmium exposure might be significantly associated with prevalence of diabetes, but large prospective studies are needed to confirm this finding.
Keywords: Diabetes; Dose-response analysis; Epidemiology; Heavy metal; Meta-analysis; Urinary cadmium.