BACKGROUND: The chronic complications of diabetes mellitus are important prognostic factors of diabetics. The pathogenic mechanisms have not been known exactly and the prevalence is different according to the race and the reporter. In general, the development of diabetic microangiopathy depends on the duration and the severity of disease, while that of macroangiopathy does not. This study was undertaken to investigate the prevalence of diabetic chronic complications according to age and duration of diabetes and to elucidate associated factors and correlation of chronic complications. METHODS: We studied 1,270 patients with non- insulin dependent diabetes mellitus (NIDDM) who visited the Endocrine-metabolism clinic at Kyungpook National University during the period from February 1992 to September 1996. We investigated prevalence, severity, associated factors and correlation of chronic vascular complications, including micro- and macroangiopathy. RESULT: 1) The ratio of male to female was similar and the average duration was 7.8 years. Diabetes mellitus was most prevalent in the 6th decade and the 1-5 years of diabetes duration. 2) The prevalences of retinopathy, nephropathy and peripheral polyneuropathy were 47.8%, 31.9% and 41.0%, respectively. Macrovascular complications were found in 6.2% of patients and the prevalences of coronary artery disease, cerebrovas-cular disease and peripheral artery disease were 2.4%, 3.4%, 0.4%, respectively. Prevalence of diabetic foot was 4.4%. 3) The prevalence and severity of microvascular complications increased as the age and diabetic duration of patients increased. In the group of same age, the prevalence of microvascular complications increased as the duration of diabetes increased. However, prevalence of macrovascular complica-tions especially coronary artery disease depended on the age, but not the duration of diabetes (p<0.05). 4) In the group over 10 years of diabetes, the fasting blood glucose, age and serum creatinine levels were increased, while hemoglobin and total protein levels were decreased than other groups (p<0.05). 5) The development of diabetic retinopathy was related to the duration, fasting blood glucose, albumine excretion rate and serum creatinine. The nephropathy was related to the duration and systolic blood pressure. The peripheral polyneuropathy was related to the duration, fasting blood glucose and body mass index. Macrovascular complications-particularly, coronary artery disease-were related to the age of diabeties (p<0.05). 6) There was significant relation between development of retinopathy, nephropathy and neuropathy but no relation between development of micro and macrovascular complications (p<0.05). CONCLUSION : The prevalence of microvascular complications in non-insulin dependent diabetics increased as the duration and the age of diabetics increased. The development of microvascular complications was related to the duration of disease and the glycemic control. There was relation between development of retinopathy, nephropathy and neuropathy. The development of macrovascular complications, however, was related to the age of diabetics but not to the microvascular complications. Our results suggest that different pathogenic mechanisms may be involved in the development of micro- and macrovaseular complications of diabetes mellitus.