Cadmium exposure in relation to insulin production, insulin sensitivity and type 2 diabetes: a cross-sectional and prospective study in women.

BACKGROUND: Cadmium is a wide-spread pollutant. Observational studies suggest associations between cadmium and prevalence of type 2 diabetes. Experimental studies indicate that cadmium may cause impaired insulin production.
OBJECTIVES: To examine whether cadmium exposure is associated with impaired glucose tolerance and type 2 diabetes and impaired pancreatic beta-cell function.
METHODS: Oral glucose tolerance tests were used in a screening examination of 64-year old women (n=2595) to identify all with diabetes, impaired (IGT) and normal (NGT) glucose tolerance. Random samples of women with type 2 diabetes (n=215), IGT (n=207) and NGT (n=194) were recruited in a cross-sectional examination including measurement of pancreatic insulin production (acute insulin response) and insulin sensitivity (homeostasis model assessment). Cadmium concentrations were measured in blood and urine. A follow-up examination was performed after 5.4 years with assessment of new cases with diabetes or impaired glucose tolerance.
RESULTS: At baseline, neither blood nor urinary cadmium concentrations showed any statistically significant differences between women with type 2 diabetes, IGT or NGT. The prospective analysis included 68 cases with incident diabetes, 58 with IGT and 118 women with NGT and no associations with cadmium levels at baseline were observed. Blood and urinary cadmium at baseline were not associated with insulin production, blood glucose, HbA1c, or changes in HbA1c during follow-up.
CONCLUSIONS: This is the first study of cadmium and diabetes with detailed data on pancreatic beta-cell function, insulin sensitivity and glucose tolerance. Cadmium exposure was not associated with increased risk of type 2 diabetes or IGT.