Magnesium deficiency and increased fractional magnesium excretion in insulin-dependent diabetes mellitus: magnesium loading test and blood pressure

Background: There is experimental and clinical evidence giving importance to the relationship between magnesium (Mg) and diabetes mellitus. The American Diabetes Society suggested that attention be given to the diagnostic significance of a Mg deficiency in diabetes mellitus. Because of regional differences in Mg supply, we studied Mg status in the surroundings of Lubeck in healthy persons as compared to diabetics. Patients and methods: 27 healthy controls (C) and 27 inpatients with an insulin-dependent diabetes mellitus (DM) and bad metabolic control were studied. Mg ++ was measured by atomic absorption spectroscopy (Video 12 apparatus) in serum and erythrocytes; basic 24-hour urinary Mg excretion (b-Mg-u), fractional Mg excretion (f-Mg-u) were calculated. In addition the Mg loading test (Mg-lt) was applied. Results: In diabetics a hypomagnesemia was observed as compared to healthy subjects both in serum (0.73 ± 0.04 vs 0.83 ± 0.04 mmol/l, means ± SD, p < 0.05) and in red blood cells (1.43 ± 0.16 vs 1.84 ± 0.10 mmol/l)(p<0.01). The b-Mg-u was 2.75 ± 3.62 mmol/d in DM as compared to 5.84 ± 2.21 mmol/d in controls (p < 0.05); f-Mg-u was 5.83 ± 2.73% in DM and 3.46 ± 1.33% in controls. The percent retention of the given Mg load was 24.5 ± 18 in DM and -41 ± 12 in controls (p < 0.001). Discussion: In DM with bad metabolic control there is convincing evidence of a Mg-deficiency. Higher f-Mg-u in case of lower S-Mg in diabetics indicate an inadequate renal Mg loss which significantly correlates with the amount of glucosuria as one of the relevant pathophysiological mechanisms.