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

Abstract

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.In 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. The prevalence of positive TMA in IDD patients was not significantly different from that in NIDD patients (4.5% vs. 2.8%; P = NS). Basal serum C-peptide and Cpeptide response to glucagon in IDD patients were similar in patients with and without ICA. Although there was a trend toward higher levels of basal C-peptide in NIDD patients positive for ICA compared to patients negative for ICA, the difference did not reach statistical significance (1.07 ± 0.36 vs. 0.62 ± 0.19 pmol/ml, respectively; P = NS).These findings, suggesting a lower prevalence of ICA and TMA in IDD patients of Mexican-American origin compared to Caucasian IDD patient populations in Europe and the United States, may indicate ethnic differences and the possible genetic heterogeneity of IDD populations. Residual B-cell function in IDD patients did not correlate with the presence or absence of ICA. However, in NIDD patients, C-peptide levels were found to be significantly increased in patients with or without ICA. This latter finding may be explained in part by the known hyperinsulinemic state in NIDD patients and may not be related directly to ICA. (J Clin Endocrinol Metab 54: 949, 1982)

Autoantibodies and High-Risk HLA Susceptibility Markers in First-Degree Relatives of Brazilian Patients with Type 1 Diabetes Mellitus: A Progression to Disease Based Study

“…These results are in agreement with a general consensus of a greater prevalence of autoimmunity against pancreatic antigens in Caucasians [40,41]. Several recent studies suggest that the prevalence of islet autoantibodies in parents and siblings of Mexican-American patients with T1DM is not different than described in Caucasians [23,42], probably due to significant genetic contribution from the Spanish-European ancestry [43].…”

Antinuclear antibodies in childhood diabetics.

“…Twenty-nine out of 80 childhood diabetics (36.3%) were positive for ICA. About a half the number of childhood diabetics had had diabetes for less than three years and the incidence of ICA was about the same as in other reports (Pujor-Borrell et al, 1978;Lendrum et al, 1976;Ziedler et al, 1982). Four out of twenty-nine cases with ICA (13.8%) were positive for ANA.…”

Thyroid autoimmunity in Type 2 (non-insulin-dependent) diabetic patients of Caucasoid, black and Mexican origin

“…A previous study which determined thyroid microsomal antibody (TMA) status in Mexican American patients with Type 2 diabetes reported a 2.8% prevalence [1]. Other studies reported 9.2% and 9.1% frequencies of thyroid antibodies in Type 2 diabetes, which were similar to the frequency seen in control subjects.…”