Research

Exposure to arsenic in drinking water is associated with increased prevalence of diabetes: a cross-sectional study in the Zimapán and Lagunera regions in Mexico

Luz M Del Razo¹, Gonzalo G García-Vargas², Olga L Valenzuela¹, Erika H Castellanos¹, Luz C Sánchez-Peña¹, Jenna M Currier³, Zuzana Drobná⁴, Dana Loomis⁵ and Miroslav Stýblo^4*

• * Corresponding author: Miroslav Stýblo styblo@med.unc.edu

Author Affiliations

¹ Departamento de Toxicología, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México DF, México

² Facultad de Medicina, Universidad Juárez del Estado de Durango, Gómez Palacio, Durango, México

³ Curriculum in Toxicology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA

⁴ Department of Nutrition, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA

⁵ School of Community Health Sciences/MS-274, University of Nevada, Reno, Nevada, USA (Current affiliation: Department of Epidemiology and Eppley Cancer Institute, University of Nebraska Medical Center, Omaha NE, USA

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Environmental Health 2011, 10:73 doi:10.1186/1476-069X-10-73

Published: 24 August 2011

Abstract

Background

Human exposures to inorganic arsenic (iAs) have been linked to an increased risk of diabetes mellitus. Recent laboratory studies showed that methylated trivalent metabolites of iAs may play key roles in the diabetogenic effects of iAs. Our study examined associations between chronic exposure to iAs in drinking water, metabolism of iAs, and prevalence of diabetes in arsenicosis-endemic areas of Mexico.

Methods

We used fasting blood glucose (FBG), fasting plasma insulin (FPI), oral glucose tolerance test (OGTT), glycated hemoglobin (HbA1c), and insulin resistance (HOMA-IR) to characterize diabetic individuals. Arsenic levels in drinking water and urine were determined to estimate exposure to iAs. Urinary concentrations of iAs and its trivalent and pentavalent methylated metabolites were measured to assess iAs metabolism. Associations between diabetes and iAs exposure or urinary metabolites of iAs were estimated by logistic regression with adjustment for age, sex, hypertension and obesity.

Results

The prevalence of diabetes was positively associated with iAs in drinking water (OR 1.13 per 10 ppb, p < 0.01) and with the concentration of dimethylarsinite (DMAs^III) in urine (OR 1.24 per inter-quartile range, p = 0.05). Notably, FPI and HOMA-IR were negatively associated with iAs exposure (β -2.08 and -1.64, respectively, p < 0.01), suggesting that the mechanisms of iAs-induced diabetes differ from those underlying type-2 diabetes, which is typically characterized by insulin resistance.

Conclusions

Our study confirms a previously reported, but frequently questioned, association between exposure to iAs and diabetes, and is the first to link the risk of diabetes to the production of one of the most toxic metabolites of iAs, DMAs^III.