Evidence of a Relationship Between Childhood-Onset Type I Diabetes and Low Groundwater Concentration of Zinc

OBJECTIVE Zinc deficiency has shown to increase the risk for diabetes in diabetes-prone experimental animals. Low concentrations of zinc have also been shown in serum of recent onset cases with IDDM. The present study examines the hypothesis that exposure to a low concentration of zinc in drinking water could increase the risk for future onset of IDDM.

RESEARCH DESIGN AND METHODS Using the Swedish childhood diabetes registry and data on residence 3 years before the onset of disease, a case-control study was designed comparing cases and control subjects with estimates of groundwater contents of zinc obtained in biogeochemical samples from areas of residence.

RESULTS A high groundwater concentration of zinc was associated with a significant decrease in risk (odds ration [OR] = 0.8; 95% CI = 0.7–0.9). The same OR was obtained when the model included information of other metals that might act as possible confounders (chromium, vanadium, cobalt selenium, cadmium, lead, and mercury). In small rural areas, in which drinking water is taken from local wells and thus is closely associated with the groundwater content within the area, an even stronger association between zinc and diabetes (OR = 0.6; 95% CI = 0.4–0.9) was found.

CONCLUSIONS It is concluded that this study for the first time provides evidence that a low groundwater content of zinc, which may reflect long-term exposure through drinking water, is associated with later development of childhood onset diabetes.