RESUMEN
BACKGROUND: Magnesium acts as a cofactor in many intracellular reactions including phosphorylation of the insulin receptor; therefore, its imbalance can potentially cause insulin resistance. Low serum magnesium concentration has been associated with the development of metabolic syndrome and type 2 diabetes mellitus. OBJECTIVE: To study the association between the daily dietary magnesium intake and insulin resistance estimated by the homeostatic model assessment of insulin resistance and homeostatic model assessment 2, as well as insulin sensitivity estimated by the Matsuda index. METHODS: In a university affiliated medical center, 32 participants (22 women, 10 men) that had an indication for testing for type 2 diabetes mellitus with an oral glucose tolerance test were enrolled in this cross-sectional, comparative study. Clinical and biochemical evaluations were carried out including an oral glucose tolerance test. Hepatic insulin resistance index, homeostatic model assessment 2, homeostatic model assessment of insulin resistance, and Matsuda insulin sensitivity were calculated for each participant. They were asked to recall their food ingestion (24 hours) of three days of the past week, including a weekend day; magnesium intake was calculated according to the food nutritional information. RESULTS: The low dietary magnesium intake group (< 4.5 mg/kg/day) had a higher two-hour insulin concentration after an oral glucose tolerance test compared to those with high dietary magnesium (119.5 [73.0-190.6] vs. 63.5 [25.4-114.2]; p = 0.008), and insulin sensitivity assessed by the Matsuda index was higher in the high dietary magnesium intake group (4.3 ± 3.1 vs. 2.4 ± 1.5; p = 0.042). In multiple linear regression analysis a higher dietary magnesium intake was independently associated (ß = 4.93; p = 0.05) with a better insulin sensitivity estimated by the Matsuda index. CONCLUSIONS: Our results suggest that higher magnesium intake is independently associated with better insulin sensitivity in patients at risk for type 2 diabetes mellitus.