Demonstration of islet cell antibodies in apparently non-insulin dependent diabetic patients; a marker for the later development of insulin dependency.

One hundred and ten diabetic patients who were apparently non-insulin dependent at 1984 were followed up for 5 years from 1984 to 1989. Islet cell antibodies (ICA) of the patients were tested in 1987. Eleven patients were positive for ICA and 99 were negative. There was no significant difference in age, sex, duration of diabetes, and HbA1c levels between ICA-positive and negative groups. Six of 11 (54.5%) patients in ICA-positive group developed insulin-requiring state in the period from 1984 to 1989, while only 5 of 99 (5.1%) patients in ICA negative group became insulin-requiring. Glucagon tolerance test (1 mg i.v.) was performed on 8 patients who developed insulin-requiring state; among them 4 patients were ICA-positive and other 4 patients were ICA negative. The serum C-peptide response to intravenous glucagon injection was markedly decreased in 3 of the 4 ICA-positive patients, and only mildly decreased in all the 4 ICA-negative patients. The markedly decreased C-peptide response indicates that these ICA-positive subjects had developed insulin-dependency. We conclude that the presence of ICA in apparently non-insulin dependent diabetics indicates a high risk for developing insulin-dependency.