Diabetes mellitus is a chronic disease which many factors are involved and is developing considerably worldwide. Increasing aging population and obesity in the societies has improved the scale of the type 2 diabetes significantly. The aim of this study was to determine the direct medical costs of outpatient cares of diabetes in Iran. Active patients of Isfahan Endocrinology and Metabolism Research Center (IEMRC) by the end of March 2011 were employed for data extraction. Type 2 diabetics were classified into 4 groups based on their therapeutic regimens. Type and frequency of health care services were extracted from the patients' profiles manually. The incidence of major diabetes complications were also examined from the subjects' profiles. The numbers of services used by the patients in different treatment groups were multiplied by the desired medical tariffs to calculate the direct medical costs. 2898 number of cases was reviewed in this study; 63.8 % women and 36.2% men. 4.3% of the patients were placed group I; 50.1% in group II, and 34.6% and 11% in groups III and IV respectively. The age distribution of the patients varied widely from 30 to 90 years; 5.8% between 30 and 39 years, 62.3% between 40 and 59, and 31.9% at 60 and over. Nephropathy (72.4%), and neuropathy (39%) were the most frequent adverse effect between the type 2 diabetics in Isfahan. The group III with spending $192.3 in total was absorbed the highest amount of the resources between the patients' groups. The average direct medical cost of outpatient cares of diabetics per year was 155.8 US $. The direct medical cost of diabetes management is progressed sharply in past years in Iran. Pharmaceutical expenditures was the main cost component of outpatient cares for diabetes. It is estimated that the Iranians directly spend approximately $4.05 milliard annually to manage 5.2 million diabetics in the country.