A case-cohort study of cadmium body burden and gestational diabetes mellitus in American women

Abstract

Background: Environmental cadmium (Cd) exposure is associated with type 2 diabetes. However, the association of Cd and gestational diabetes mellitus (GDM) is unknown. Objectives: We examined the association between body burden of Cd and GDM risk. Methods: We used 140 GDM cases and 481 randomly selected noncase subcohort members from the Omega Study to conduct a case-cohort study. Creatinine (Cr)–corrected Cd in early pregnancy urine (U-Cd) was measured by inductively coupled plasma mass spectrometry. Tertiles (< 0.29; 0.29–0.42; ≥ 0.43 μg/g Cr) were defined using the subcohort’s U-Cd distribution. GDM was diagnosed using the 2004 American Diabetes Association guidelines. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using logistic regression. Results: GDM cases had higher geometric mean U-Cd (0.39 μg/g Cr; 95% CI: 0.37, 0.41) than noncases (0.31 μg/g Cr; 95% CI: 0.29, 0.33). Odds ratios for GDM increased with increasing U-Cd tertile (OR = 1.64; 95% CI: 0.88, 3.05 for middle vs. low tertile; OR = 2.07; 95% CI: 1.15, 3.73 for high vs. low tertile; p-trend = 0.015). Overweight/obesity (body mass index ≥ 25 kg/m 2) did not modify the association between U-Cd and GDM (p = 0.26). Conclusions: Our findings suggest that body burden of Cd increases risk of GDM in a dosedependent manner. Improved understanding of environmental factors influencing GDM may facilitate early identification of women at high risk of GDM.