Association between Toenail Magnesium and Type 2 Diabetes in Chinese Adults

Previous studies have showed an inverse association between magnesium level and type 2 diabetes, but the results are inconsistent, and the evidence relates only to dietary and serum magnesium. Moreover, it is not certain how these findings are applicable to Asian people. This study was designed to examine the association between toenail magnesium and type 2 diabetes in Chinese adults. The sample was 5683 adults aged 18 years or older from the 2009 China Health and Nutrition Survey. We used hemoglobin A1c equal to or greater than 6.5% as the diagnostic criterion for type 2 diabetes. Inductively coupled plasma–mass spectrometry determined toenail magnesium. Mean toenail magnesium in participants with and without type 2 diabetes was 263.0 ± 170.9 and 282.3 ± 191.9 micrograms per gram, respectively. The multivariable-adjusted odds ratio for type 2 diabetes comparing the highest to the lowest quartile of toenail magnesium was 0.72 (95% confidence interval, 0.52–0.99). We found a statistically significant interaction between toenail magnesium and geographic region on the prevalence of type 2 diabetes (p for interaction = 0.009). Our findings suggest that toenail magnesium is inversely associated with the prevalence of type 2 diabetes. Promoting the intake of magnesium-rich foods may bring considerable benefits for the prevention of type 2 diabetes, especially in those at high risk.