Data on primary prevention of
zinc status and diabetes risk are sparse and inconsistent. Of note, the previous studies measured either dietary
zinc intake with questionnaire or
zinc status in serum or hair. Toenail
zinc levels are reliable
biomarkers of a relatively long-term exposure. A total of 3,960 American young adults, aged 20-32 years, free of diabetes at baseline in 1987 when toenail clippings were collected, were examined for incident diabetes through 2010. Toenail
zinc levels were measured with an inductively-coupled-plasma mass spectroscopy method. Incident diabetes cases were identified by fasting or non-fasting plasma
glucose levels, oral
glucose tolerance tests,
hemoglobin A1C levels, and/or
antidiabetic medications. During the 23-year follow-up, 418 incident diabetes occurred. After adjusted for age, sex, ethnicity, study center, body mass index, education, smoking status, alcohol consumption, physical activity, family history of diabetes, homeostasis model assessment of
insulin resistance, and other dietary and non-dietary potential confounders, the hazard ratio of incident diabetes comparing the highest to the lowest quartile of toenail
zinc levels was 1.21 (95% CI: 0.90-1.63; Ptrend = 0.20). Findings from this study do not support the hypothesis that
zinc status is inversely and longitudinally associated with the incidence of diabetes in American young adults.