Determinants of hypomagnesemia in patients with type 2 diabetes mellitus.

BACKGROUND Hypomagnesemia (plasma magnesium (Mg2+) concentration <0.7 mmol/L) has been described in patients with type 2 diabetes. Polypharmacy is inevitable when treating a complex disease such as type 2 diabetes and could explain disturbances in the plasma Mg2+ concentration. In this study, we aimed to establish the extent of hypomagnesemia in a cohort of type 2 diabetes patients and to identify the determinants of plasma Mg2+ levels. METHODS Patient data and samples of 395 type 2 diabetes patients were investigated. Plasma Mg2+ concentrations were measured using a spectrophotometric assay. Using Pearson correlation analyses, variables were correlated to plasma Mg2+ levels. After excluding confounding variables, all parameters correlating (P < 0.1) with plasma Mg2+ were included in a stepwise backward regression model. RESULTS The mean plasma Mg2+ concentration in this cohort was 0.74 ± 0.10 mmol/L. In total, 121 patients (30.6%) suffered from hypomagnesemia. Both plasma triglyceride (r = -0.273, P < 0.001) and actual glucose levels (r = -0.231, P < 0.001) negatively correlated with the plasma Mg2+ concentration. Patients using metformin (n = 251, 62%), proton pump inhibitors (n = 179, 45%) or β-adrenergic receptor agonists (n = 31, 8%) displayed reduced plasma Mg2+ levels. Insulin use (n = 299, 76%) positively correlated with plasma Mg2+ levels. The model predicted (R2) 20% of all variance in the plasma Mg2+ concentration. CONCLUSIONS Hypomagnesemia is highly prevalent in type 2 diabetes patients. Plasma triglycerides and glucose levels are major determinants of the plasma Mg2+ concentration, whereas only a minor part (<10%) of hypomagnesemia can be explained by drug intake, excluding polypharmacy as a major cause for hypomagnesemia in type 2 diabetes.