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Diabetes commonly is associated with CAD risk factors, in addition sub-optimal metabolic control of diabetes is associated with increased incidence of thyroid function disorders. In this study patients with diabetes type II who were referred to 5th Azar Hospital in Gorgan were assessed to find out the relationship between thyroid dysfunction and NIDDM in such patients in Gorgan. We studied 210 diabetic patients in hospital outpatient department. The blood pressure, height, weight, serum total Cholesterol, Triglycerides, fasting blood sugar, and glycosylated hemoglobin (HbA1c) were determined. The obesity (BMI>30) were seen in 35% of the subjects. Hypertension and hyperlipidemia were seen in 38 and 65 of our patients respectively. The observed disorders included goiter (30%), sub-clinical hypothyroidism (13%), clinical hypothyroidism (4%), and clinical hyperthyroidism (0.5%). The patients were divided into two groups according to HbA1c: Group 1 with HbA1c<8 and group II with HbA1c?8. A significant difference was observed in TSH serum concentration between group I and II (1.5±1.2 vs. 3.7±11.3 mu/l, P<0.05), whereas the concentration of T4 (10±11 vs. 11±8) and T3 (2.4±3.7 vs. 1.9±3.2) were not significantly different between the two groups. The mean concentration of HbA1c in patients with hypothyroidism was significantly higher than those that of non-hypothyroid subjects (11±2.5 vs. 9±2.5, P<0.005). A significant positive correlation was observed between HbA1c concentration and TSH levels (R=0.2, P<0.01). Our results confirm the association between thyroid dysfunction and uncontrolled diabetes mellitus. It has been recommended that the final diagnosis of thyroid function disorder in diabetic patients should be made after optimal metabolic status has been archived.