ABSTRACT Objective Type 2 diabetes mellitus (T2DM) is a worldwide health problem, and medical nutrition therapy is essential for improving the quality of life of patients with type 2 diabetes. Salt restriction may lead to iodine deficiency in these patients. Moreover, type 2 diabetes can be an indirect reason for thyroid disorders. This study was conducted to determine the relationship between dietary iodine intake, urinary iodine excretion and thyroid functions in people with T2DM. Materials and methods Iodine nutritional status was determined by a one day 24-h dietary recall and food-frequency questionnaire. Iodine status was detemined by urinary iodine excretion with morning urine sample. Results Iodine intake according to one day 24-h dietary recall was lower in T2DM patients [94.8 (76.0-112.0) μg] than people in control group [137.1 (123.1-165.4) μg] (p < 0.05). Iodine intake determined by food-frequency questionnaire rich in iodine was lower in T2DM patients [93.1 (84.4-113.9) μg] than people in control group [140.2 (125.1-166.1) μg] (p < 0.05). Mild iodine deficiency was found in %38.8 of diabetic and %55.1 of healthy individuals (p < 0.05). No significant relationship was found between urinary iodine excretion and thyroid function tests in groups (p > 0.05). However, the relationship between dietary iodine excretion and urinary iodine intake in the diabetic group was lower than in the control group (p < 0.05). Conclusion With this respect, the results showed that while planning medical nutrition therapy for diabetic individuals, the risk of iodine deficiency should be considered.