Daily magnesium supplements improve glucose handling in elderly subjects

ABSTRACT We demonstrated similar plasma concentra-tions and urinary losses but lower erythrocyte magnesium con-centrations (2. 18 ± 0.04 vs 1.86 ± 0.03 mmol/L, P < 0.01) in twelve aged (77.8 ± 2. 1 y) vs 25 young (36. 1 ± 0.4 y), nonobese subjects. Subsequently, aged subjects were enrolled in a double-blind, randomized, crossover study in which placebo (for 4 wk) and chronic magnesium administration (CMA) (4.5 g/d for 4 wk) were provided. At the end of each treatment period an in-travenous glucose tolerance test (0.33 g/kg body wt) and a eu-glycemic glucose clamp with simultaneous [D-3H]glucose in-fusion and indirect calorimetry were performed. CMA vs placebo significantly increased erythrocyte magnesium concentration and improved insulin response and action. Net increase in eryth-rocyte magnesium significantly and positively correlated with the decrease in erythrocyte membrane microviscosity and with the net increase in both insulin secretion and action. In aged patients, correction ofa low erythrocyte magnesium concentra-tion may allow an improvement ofglucose handling. Am J C/in Nutr l992;55:l 16 1-7. KEY WORDS Magnesium, glucose homeostasis, hepati