Intracellular magnesium depletion relates to increased urinary magnesium loss in type I diabetes

We investigated whether erythrocyte magnesium (Mg) depletion exists in subjects with Type I diabetes. To this end, Mg levels in plasma, erythrocytes and urine were determined in 12 patients with Type I diabetes and compared with 12 healthy control subjects. Mean plasma Mg concentrations were comparable between diabetic patients and control subjects (0.90 +/- 0.29 mmol/l vs 1.04 +/- 0.14 mmol/l, respectively; p = 0.16). Mean erythrocyte Mg concentration was significantly lower in the diabetic group compared with the control group (1.41 +/- 0.56 mmol/l vs. 2.94 +/- 1.13 mmol/l, respectively; p < 0.0001). Mean urine Mg excretion was significantly elevated in the diabetic group with respect to the controls (6.86 +/- 3.5 mmol/g creatinine/24 h vs. 4.03 +/- 1.65 mmol/g creatinine/24 h, respectively; p = 0.02). As to the diabetic group, erythrocyte Mg concentration showed a significant inverse correlation with urine Mg excretion (r = -0.58, p = 0.049). There was no correlation between urine Mg concentration and glycosylated hemoglobin or fasting plasma glucose level. The data suggest that intracellular Mg depletion without significant hypomagnesemia is related to increased urinary Mg loss in patients with Type I diabetes. The urinary Mg loss is not correlated with the degree of metabolic control.