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, less than 18 yr old at diagnosis, placed on insulin within 2 wk of diagnosis, and had diabetes not secondary to other conditions. Residual beta-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 beta-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.