Background & Objective: The prominent growth in the statistics of the patients with Diabetes Mellitus (DM) and the danger of its complication states a necessity to focus on finding new ways to control it. The present study then was performed to survey the effect of L-Arginin supplementation on the metabolism of sugar and lipid profiles in patients with diabetes type 2. Materials & Methods: In a randomized double-blind clinical trial, 75 patients with diabetes type 2 were divided into three groupsrandomly: 1. 3 gr L-Arginin per day, 2. 6 gr L-Arginin per day and 3. The placebo group. Height, weight, waist, High Density Lipoprotein (HDL), Triglycerides (TG), Low Density ipoprotein (LDL), and the total cholesterol were measured before and after three months of intervention. Results: no significant change was made in any of the lipid parameters in the intervention group. However, the two means of cholesterol and LDL decreased from169.12±34.83 mg/dl to 142.08±32.13mg/dl(P-Value<0.001) and from 96.80±35.46mg/dl to 86.64±32.65(P-Value=0.001), respectively though The changes in TG and HDL were not significant. Conclusion: Daily consumption of six gram L-Arginin during three months improves the lipid profiles in patients with Diabetes type2. Nevertheless, the dosage of three gram in a day of this supplement has no effect on the blood lipids status.