Serum ionized magnesium levels in type 2 diabetic patients with microalbuminuria or clinical proteinuria

Background/Aims: The association between microalbuminuria and magnesium dep letion is a controversial issue, and serum ionized magnesium levels have no t been previously studied in patients with different grades of diabetic nep hropathy. Therefore, the aim of th is study was to evaluate circulating ion ized magnesium concentrations in patients with non-insulin-dependent diabet es mellitus (NIDDM) and incipient or overt diabetic nephropathy. Methods: W e measured fasting plasma glucose, creatinine, creatinine clearance estimat e, total cholesterol and triglycerides, and serum ionized magnesium lion-se lective electrodes, ISE) in 30 NIDDM patients with urinary albumin excretio n rate (UAER) <20 mu g/min (normoalbuminuria), 30 NIDDM patients with micro albuminuria (20 < UAER < 200 mu g/min), 30 NDDM patients with clinical prot einuria (UAER >200 mu g/min), and 20 healthy subjects. Results: Serum ioniz ed magnesium levels were significantly reduced in diabetic patients when co mpared to control subjects (0.39 +/- 0.06 vs. 0.58 +/- 0.05 mmol/l, p < 0.0 01). Moreover, diabetic patients with microalbuminuria or clinical proteinu ria showed a significant decrease in serum ionized magnesium with respect t o normoalbuminuria group (normoalbuminuria: 0.45 +/- 0.02 mmol/l; microalbu minuria: 0.36 +/- 0.05 mmol/l, p < 0.001; clinical proteinuria: 0.35 +/- 0. 04 mmol/l, p < 0.001). Serum ionized magnesium showed a significant negativ e correlation with plasma HbA1c and triglycerides in both microalbuminuria and clinical proteinuria groups. Multiple linear regression analysis showed that circulating ionized magnesium levels decrease together with the incre ase of plasma HbA1c and triglycerides in NIDDM patients with incipient or o vert nephropathy, also after adjusting for age, sex, BMI, diabetes duration , systolic and diastolic blood pressure, hypoglycemic therapy, plasma creat inine, creatinine clearance, plasma cholesterol and fasting glucose. Conclu sions: Microalbuminuria and clinical proteinuria, as well as poor glycometa bolic control and hypertriglyceridemia, a re associated to relevant alterat ions in magnesium metabolism, and the measurement of serum ionized magnesiu m seems to represent a useful biochemical tool for the study of magnesium d isturbances in patients with different grades of diabetic nephropathy. Copy right (C) 2000 S. Karger AG, Basel.