A Case-Cohort Study of Cadmium Body Burden and Gestational Diabetes Mellitus in American Women.

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 dose-dependent manner. Improved understanding of environmental factors influencing GDM may facilitate early identification of women at high risk of GDM.