Summary

Objective Although hypomagnesemia reduces insulin sensitivity, benefits of magnesium supplementation to non-diabetic insulin resistant subjects has not been established. Our purpose was to determine whether oral magnesium supplementation with magnesium chloride (MgCl 2 ) 2.5 g daily modify insulin sensitivity in non-diabetic subjects.

Material and Methods This study was a 3 months randomized double-blind placebo-controlled trial. Apparently healthy subjects were eligible to participate if they had insulin resistance (HOMA-IR index equal or greater than 3.0) and hypomagnesemia (Serum magnesium levels equal or lower than 0.74 mmol/l). Subjects were randomized to receive either, MgCl 2 2.5 g daily or placebo by 3-months.

Results At baseline there were not significant anthropometric or laboratory differences between both groups. At ending of the study, magnesium-supplemented subjects significantly increased their serum magnesium levels (0.61 ± 0.08 to 0.81 ± 0.08 mmol/l, p < 0.0001) and reduced HOMA-IR index (4.6 ± 2.8 to 2.6 ± 1.1, p < 0.0001), whereas control subjects did not (0.62 ± 0.08 to 0.61 ± 0.08 mmol/l, p = 0.063 and 5.2 ± 1.9 to 5.3 ± 2.9, p = 0.087).