This study was conducted to draw out prevalence and the risk factors of diabetes mellitus and impaired fasting glucose for adults,(age 30-69). The subjects were 2096 adults, who had regular health examinations between January and December of 1999 at K Hospital in Seoul. The data was analyzed using chi-square test, unpaired t-test and logistic regression. Diabetes Mellitus and impaired fasting glucose were diagnosed by ADA (American Diabetes Association, 1997) criteria. The results were as follows: 1. Mens' prevalence of Diabetes Mellitus was 7.9% and womens' prevalence of Diabetes Mellitus was 3.8%. Mens' prevalence of impaired fasting glucose was 10.4% and womens' prevalence of impaired fasting glucose was 6.5%. Prevalences of Diabetes Mellitus and impaired fasting glucose increased with age. 2. Prevalence of Diabetes Mellitus and impaired fasting glucose of obese subjects (relative body weight>=162) was higher than that of overweight subjects (110<=relative body weight<=119) in men and women. 3. The diagnoses of Diabetes Mellitus and impaired fasting glucose increased with systolic blood pressure and triglyceride. 4. Significant factors associated with diabetes in the logistic regression best gut model were age, relative body weight, systolic blood pressure, triglyceride in men, and systolic blood pressure in women. In conclusion, as age, weight, systolic blood pressure and triglyceride get higher, Diabetes Mellitus and impaired fasting glucose prevalence also increases, porportionally.