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.