Aims: Diabetes screening is an effective tool for diagnosing patients who are unaware of their diabetes and for providing them with optimal treatment. The quality of care and treatment of diabetic patients diagnosed at a screening program during one year in Isfahan, a centrally located Iranian city, was assessed. Methods: In a prospective study, 1640 first-degree relatives of diabetic patients (aged 35-55) were screened for diabetes mellitus at Isfahan Endocrine and Metabolism Research Center during 2003-2004. All patients diagnosed with diabetes during screening were selected and their height, weight, blood pressure, fasting plasma glucose, lipids and HbA1c were recorded at the time of diagnosis and one year later. The values at the time of screening were subsequently compared with those collected one year later. Results: Eighty-three subjects (5.06%) were diagnosed with diabetes during screening. Of these patients, 78.3% were dyslipidemic and 45% were hypertensive. One year after diagnosis, 77.1% of patients were receiving treatment for hyperglycemia. However, only 49.2% of dyslipidemic and 45% of hypertensive patients were being treated for these conditions. Body mass index, fasting plasma glucose, lipids and HbA1c had improved one year after diagnosis, but no significant improvement was observed in blood pressure. Conclusions: The evaluation of the quality of care for newly diagnosed diabetic patients revealed that more attention should be paid to glycemic control and reducing cardiovascular risk factors, in particular hypertension.