Clinical Characteristics of IDDM in Hispanics and Non-Hispanic Whites: Little evidence of heterogeneity by ethnicity

OBJECTIVE To compare the clinical characteristics of IDDM in HD and NHWD subjects in order to evaluate potential heterogeneity of IDDM by ethnicity. RESEARCH DESIGN AND METHODS HD subjects ( n = 73) and NHWD subjects ( n = 97) were recruited from the Colorado IDDM Registry. The registry included individuals who were Colorado residents, < 18 yr old at diagnosis, placed on insulin within 2 wk of diagnosis, and had diabetes not secondary to other conditions. Residual β-cell function was measured as the 1-h C-peptide response to a Sustacal challenge. RESULTS HD subjects were similar to NHWD subjects in insulin dose, HbA1, HLA-DR antigens, ICAs, and family history of IDDM. HD subjects were more likely to have a family history of NIDDM than NHWD subjects (11 vs. 3%, P = 0.03). HD girls had higher C-peptide levels (0.27 vs. 0.11 nm/L [0.83 vs. 0.33 ng/ml], P = 0.01), BMI (22.7 vs. 20.9 kg/m2 P = 0.04), subscapular skinfold thickness (18.9 vs. 15.0 mm, P = 0.04), and WHR (0.81 vs. 0.77, P = 0.03) than NHWD females. After controlling for diabetes duration, BMI, sex, and family history of NIDDM, residual β-cell function was associated significantly with Hispanic ethnicity, although the term accounted for just 3% of the overall variability in C-peptide levels. CONCLUSIONS Little evidence of heterogeneity by ethnicity of IDDM patients in the Colorado IDDM Registry was found. Ethnic differences in C-peptide levels may be related to differences in body fat distribution in females rather than heterogeneity of the disease.