A total of 75 diabetic patients (39 men and 36 women), aged 36 to 69 years, having diabetes for at least 3 years, was recruited for this study. Type 2 diabetes was defined as fasting plasma glucose 126 mg/dl (two times repeated) or taking oral glucose-lowering agents.Diabetic patients were stratified by sex and randomly assigned to one of the three treatment groups using block randomization procedure. Depending upon the treatment groups, each subject received two capsules per day, 1 with breakfast and 1 with dinner, for a period of 4 months. Each capsule contained one of the following preparations and hence determined the corresponding groups: Group MV: Zinc sulfate and Magnesium oxide (providing 10 mg Zn and 125 mg Mg) and vitamin C (100 mg) and vitamin E (100 mg); Group MVB: both of the above mineral and vitamin supplements plus vitamin B1 (5 mg), vitamin B2 (5 mg), vitamin B6 (5 mg), biotin (50 µg), vitamin B12 (5 µg) and folic acid (0.5 mg); Group P: starch (placebo). All of the study medications, including the placebo, were supplied by Pharmaceutical Sciences Research Center (Tehran University of Medical Sciences, Iran) and were indistinguishable from each other. They were stored at 20-25 0C.