Islet cell antibodies and insulin autoantibodies in patients treated with oral hypoglycaemic agents.

Clinical and immunological features suggesting Type 1 diabetes were assessed in 202 patients treated with oral hypoglycaemic agents for presumed Type 2 diabetes. Islet cell antibodies (ICA) were detected at a level exceeding 5 JDF units in 5.9% of patients, and complement-fixing ICA were detected in 3.4%. IgG insulin autoantibodies were detected in 8.8% of insulin-naive patients, none of whom were ICA positive. ICA were detected more frequently in patients with shorter duration of diabetes (p = 0.02). Age and relative body weight were similar in ICA positive and negative groups. ICA positive patients were more likely to have lost weight (p less than 0.02) than ICA negative patients, although this may have been attributable to the differing duration of diabetes in the two groups. Other individual clinical features suggesting Type 1 diabetes were not significantly more frequent in ICA positive patients. However, a higher proportion of ICA positive than ICA negative patients had one or more features suggestive of Type 1 diabetes irrespective of the duration of diabetes. Clinical features suggesting Type 2 diabetes were present in a similar proportion of ICA positive and ICA negative patients. Fasting and glucagon stimulated C-peptide levels were similar in ICA positive and matched ICA negative patients.