Evaluation of the association between urinary cadmium levels below threshold limits and the risk of diabetes mellitus: a dose-response meta-analysis

Abstract

As cadmium levels are increasing in the environment, the adverse effects of cadmium exposure specifically associated with chronic diseases are receiving increasing attention. Several population-based studies have been conducted on the association between cadmium and diabetes mellitus (DM) but have reported controversial results. Here, we aimed to evaluate the association between cadmium exposure and DM. In this meta-analysis, a random effects model was used because there was evidence of heterogeneity among studies. A dose-response relationship was assessed through a restricted cubic spline model with three knots. The results showed a positive association between cadmium levels in the body and DM (OR = 1.27; 95% CI, 1.07-1.52). The cadmium levels in the body were defined on the basis of combined urinary and blood cadmium. Subgroup analysis further indicated a positive association between urinary cadmium levels and DM (OR = 1.31; 95% CI, 1.02-1.69). The dose-response analysis results showed a positive association between levels of urinary cadmium above 2.43 μg/g creatinine and DM, and the risk of DM increased by 16% for each l μg/g creatinine increase in urinary cadmium levels. The results from our meta-analysis indicate that cadmium levels in the body are positively associated with DM, and urinary cadmium levels above 2.43 μg/g creatinine are associated with an increased risk of DM.

Keywords: Cadmium; Diabetes mellitus; Dose-response analysis; Meta-analysis; Pancreatic β cells.