Pancreatic Islet Cell and Thyroid Antibodies, and Islet Cell Function in Diabetic Patients of Mexican-American Origin*

Two hundred and thirty-six diabetic patients of Mexican-American origin were studied for the presence of pancreatic islet cell antibodies (ICA) and thyroid microsomal antibodies (TMA). One hundred and thirty-one subjects were insulin-dependent diabetic patients (IDD; type I), and 105 were noninsulin-dependent diabetic patients (NIDD; type II). The control population consisted of 79 normal subjects with no family history of diabetes mellitus. I n addition, residual B-cell function (C-peptide) and C-peptide response to the iv administration of 1 mg glucagon were studied in IDD patients positive and neagtive for ICA. The prevalence of ICA was 25.9% in IDD patients, significantly higher than the 8.5% observed in the NIDD patients and the control population (P < 0.01). In IDD patients, the prevalence of ICA was strongly dependent on the duration of the disease and was 50% during the first year after diagnosis, 20.7% 2–5 yr after diagnosis, 11.7% 11–20 yr after diagnosis, and 2.9% over 21 yr after diagnosis. Th...