Recently the incidence of diabetic patients in Korea is increasing continuously and the pattern is changing in several aspects. To study the changing in pattern of diabetic incidence, authors evaluated the 5601 cases of diabetic patients, who registered as diabetic to Diabetic Clinic. Seoul National University Hospital, from 1957 to 1977. Followings are the results: 1. The incldence of diabetic patients among the patients in the Department of Internal Medicine was 1.51% and the anaual incidence analysis revealed linearly increasing pattern, and the increase was statistically significant (r=0.92. P<0.001). 2. Male to female sex ratio was 1.74 : 1, and the annual decline of sex ratio was linear and significant (r=0.67 p<0.05) 3. The distribution of diabetic patients by age is as follows : 3rd decade 5.4%, 4th decade 19.1%,5th decade 33.2%, 6th decade 28.4% and 7th decade 10.4%. But the incidence of 6th and 7th decade diabetic patients seemed to increasing in these 3~4yrs and 6th decade patients were most prevalent in these days. 4.Positive family history of diabetes was recognized in 17.1% of diabetic patients and 1% of patients were composed of secondary diabetes. Steroid abuse contributed a half of the secondary diabetes cases. 5. Eight percent of observed patients lived at the capital city and the two third of the patients were of mid to high socio-economic ststus.