Oral magnesium supplementation improves insulin sensitivity and metabolic control in type 2 diabetic subjects: a randomized double-blind controlled trial

Relaxatory effect of magnesium on mesenteric vascular beds differs from normal and streptozotocin induced diabetic rats

Magnesium deficiency has recently been proposed as a novel factor implicated in the pathogenesis of diabetes complications. Previous studies have shown that magnesium decreases basal tone in normal isolated aortic rings and reduces phenylephrine-induced contraction. The mechanism of this magnesium action is not very well known. The present study was designed to determine the role of endothelium and nitric oxide in magnesium sulfate-induced vasorelaxation in diabetic rat vessels. Diabetes was induced by a single tail injection of streptozotocin. Eight weeks later, superior mesenteric arteries of control and diabetic animals were isolated and perfused according to the McGregor method. Prepared vascular beds were constricted with phenylephrine to induce 70-75% of maximal constriction. Magnesium sulfate at concentrations of 0.001 M to 0.1 M was added into the medium and perfusion pressure was then recorded. Mesenteric bed baseline perfusion pressure in intact and denuded endothelium of diabetic groups was higher than controls. In all groups, relaxant response to magnesium in mesenteric bed was attenuated after endothelium removal, but a relaxatory effect appears at high concentration. In the presence of N (omega)-nitro-L-arginine methyl ester (L-NAME), magnesium-induced relaxation was significantly suppressed in intact mesenteric bed of control animals but in diabetics, the relaxant response was slightly inhibited. From the results of this study, it can be concluded that magnesium-induced endothelium dependent and endothelium independent vasorelaxation are mediated by nitric oxide in control rats while in diabetic animals other mechanisms may be involved.

Study of magnesium, glycosylated hemoglobin and lipid profile in diabetic retinopathy

The present study was undertaken in 100 subjects, 30 diabetics without complication (group I), 40 diabetics with retinopathy (group II) and 30 non diabetic as normal control group (group III). Blood sugar levels, magnesium, cholesterol and triglyceride were analyzed from plasma and serum. The results were correlated with degree of diabetic control from the levels of glycosylated hemoglobin. Serum magnesium levels in group II were found to be significantly lowered than in group I. There was also significant difference in magnesium levels of group I and group III. We found a significant correlation between the glycosylated hemoglobin and magnesium levels in our study.The results also indicate that the patients with diabetic retinopathy showed significant rise in serum cholesterol and triglyceride. Probably hypomagnesemia and increased serum cholesterol and triglyceride levels are responsible for microvascular changes in diabetes leading to retinopathy. The purpose of this study was thus to gather information about the degree of control of diabetes and magnesium status.

Oral Magnesium supplementation improves insulin sensitivity in non-diabetic subjects with insulin resistance. A double-blind placebo-controlled randomized trial

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 (MgCl2) 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, MgCl2 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).

CONCLUSIONS

Oral magnesium supplementation improves insulin sensitivity in hypomagnesemic non-diabetic subjects. Clinical implications of this finding have to be established.