Introduction: This study aimed to evaluate the effect of oral supplementation of cinnamon on glucose control index and lipid profile in type II diabetic patients.Methods: The present study was a randomized trial on 75 patients with type II diabetes mellitus (30 patients in cinnamon group and 45 patients in control group), in Karaj-Iran during 2010 to 2012. The two groups were given 90 days cinnamon and placebo capsules (starch) (500 mg, twice a day after breakfast and lunch). Vein blood samples were taken at the beginning and end of study to measure fasting blood glucose (FBG), two-hour blood glucose (BS2hpp), glycated hemoglobin (HbA1c), insulin serum, Triglyceride, total Cholesterol and its contents. Using HOMA Score, insulin resistance was also measured. The Chi square test, t-test, ANOVA and SPSS software were used to analyze the data.Result: At the end of intervention, a significant reduction was seen in BMI in the cinnamon group compared to placebo (p=0.01).While there wasn’t a significant difference in other variables. Also, in patients receiving cinnamon, the mean of FBG, BS2hpp, HbA1c, serum insulin, HOMA score and BMI was significantly more different than before the intervention (p<0.05 for all items).Conclusion: Although it did not appear that oral supplementation of cinnamon, alone reduced the glucose and lipid blood parameters in type II diabetic patients, nevertheless, its supplementation in order to adjust the weight of diabetic patients with conventional therapy is recommended.