Comparison of the effects of vitamins and/or mineral supplementation on glomerular and tubular dysfunction in type 2 diabetes

Abstract

OBJECTIVE - The present study was designed to assess the effect of magnesium plus zinc, vitamins C plus E, and a combination of these micronutrients on nephropathy indexes in type 2 diabetic patients. RESEARCH DESIGN AND METHODS - In a randomized, double-blind, placebo-controlled clinical trial, 69 type 2 diabetic patients were randomly divided into four groups, each group receiving one of the following daily supplement for 3 months: group M (n = 16), 200 mg Mg and 30 mg Zn; group V (n = 18), 200 mg vitamin C and 100 IU vitamin E; group MV (n = 17), minerals plus vitamins; and group P (n = 18), placebo. Urinary albumin excretion and N-acetyl-β-D-glucosaminidase activity (NAG) in urine were determined at the beginning and at the end of the trial. Treatment effects were analyzed by general linear modeling. RESULTS - Results indicate that after 3 months of supplementation, levels of urinary albumin excretion decreased in the V and MV groups (P = 0.034 and P = 0.005, respectively). Urinary NAG activity did not significantly change in any treatment groups. Levels of systolic, diastolic, and mean blood pressure significantly decreased in the MV group (P = 0.008, P = 0.017, and P = 0.009, respectively). Also, combination of vitamin and mineral supplementation had significant effects in decreasing fasting serum glucose (P = 0.035) and malondialdehyde concentrations (P = 0.004) and in increasing HDL cholesterol and apolipoprotein A1 levels (P = 0.019). There was no significant change in the levels of these parameters in the other three groups. CONCLUSIONS- In conclusion, the results of the present study provide evidence for the effects of vitamins C and E and also combination of magnesium, zinc, and vitamins C and E supplementation on improvement of glomerular but not tubular renal function in type 2 diabetic patients. © 2005 by the American Diabetes Association.