Objective: CA 72-4 is one of the blood group carbohydrate antigens which can be used as a tumour marker in ovarian, pancreatic and gastrointestinal carcinomas. It can also be elevated in various benign conditions including pancreatitis. Diabetes mellitus is a chronic disorder related with the pancreas. In this study, we investigated CA 72-4 levels in patients with type 2 diabetes and its relation to the metabolic status. Methods: Sixty-nine patients with type 2 diabetes mellitus (female/male = 40/29) and 60 healthy subjects (female/male = 35/25) participated in this study. The levels of serum CA 72-4 were measured and faecal occult blood tests (following 3 days of white diet were obtained for three consecutive days) were performed in all patients. Patients had a pathological finding for any of these two parameters were further investigated with upper gastrointestinal endoscopy, colonoscopy and computerised tomography. Results: The mean levels of CA 72-4 was 1.89 +/- 2.61 U/ml in the study group and 1.4 +/- 0.98 U/ml in the control group (p > 0.05). There was no association between CA 72-4 levels and age and sex of the patients, duration of diabetes, body mass index, biochemical indicators of metabolic control (the levels of HbA(1c), fasting and postprandial glucose, serum lipids), the presence of microvascular complications (retinopathy, nephropathy, neuropathy) or treatment modalities. Conclusions: Elevated levels of CA 72-4 in diabetic patients are not related to diabetes and it should be interpreted as evaluated in a non-diabetic patient.