Type 2 diabetes occurrence and mercury exposure - From the National Nutrition and Health Survey in Taiwan

Background: The global prevalence of type 2 diabetes continues to increase in both developed and developing countries. Environmental exposure to mercury may be an important and modifiable risk factor for type 2 diabetes. However, the epidemiological results are controversial. Objectives: This study aimed to examine the association between blood mercury levels and prevalence of type 2 diabetes. Methods: A total of 646 adult participants were selected from the National Nutrition and Health Survey in Taiwan (NAHSIT) 2005-2008. The participants were interviewed using structured questionnaires to record data on basic demographics, socioeconomic status, lifestyle, medical history, and 24-h dietary recall. Specimens of blood and urine were collected at the health examination. Type 2 diabetes was defined as a fasting blood glucose level >= 126 mg/dL or intake of hypoglycemic medications. The mercury concentration in red blood cells (RBC-Hg) was quantified by cold vapor atomic absorption spectrometry. Results: Participants with type 2 diabetes had a significantly higher RBC-Hg than those without type 2 diabetes. A significant association between the RBC-Hg and prevalence of type 2 diabetes was observed [odds ratio (OR): 1.64; 95% confidence intervals: 1.14-2.35] after potential confounders were well considered, including age, sex, body mass index (BMI), hypertension, total cholesterol, saltwater fish consumption, geographical strata, seasonality and hemoglobin (Hb) level. Conclusion: Our findings showed that elevated RBC-Hg is significantly associated with type 2 diabetes prevalence. Future research, particularly for longitudinal cohort studies with suitable specimens, needs to be performed to verify our findings.