Colorado IDDM Registry: Lower Incidence of IDDM in Hispanics Comparison of Disease Characteristics and Care Patterns in Biethnic Population

The Colorado IDDM Registry identifies newly diagnosed cases of insulin-dependent diabetes mellitus (IDDM) throughout the state. Hispanics in Colorado are a racial mixture of American Indian and White populations. Because American Indians have a low risk of IDDM, and differing frequencies of HLA antigens and haplotypes are reported for Hispanics and non-Hispanics, we compared incidence rates and disease characteristics. Eligible participants were <18 yr of age and Colorado residents at time of diagnosis, diagnosed between 1 January 1978 and 31 December 1983, and on insulin within 2 wk of diagnosis. Subjects were reported by their physicians, and statewide validation of reporting was conducted through review of hospital discharge indexes. Incidence rates for Hispanics (n = 76) were significantly lower than those for non-Hispanics (n = 628), although 95% confidence intervals overlapped for children aged 10–17 yr. Age-adjusted rates were significantly lower in Hispanic than non- Hispanic males, whereas age-adjusted rates for females did not differ. The cumulative risk of IDDM was less for Hispanic males aged 0–17 yr than for non-Hispanic males (P < .001); cumulative risk among females was not different (P = .10). Clinical onset characteristics and medical care at diagnosis were similar. After diagnosis, hospitalizations per 100 person-yr appeared higher in Hispanics, but ketoacidosis and insulin reactions per 100 person-yr were similar. Difference in rate of hospitalizations may have been due to lower response rates among older non-Hispanics. From the data, it appeared that Hispanics and non-Hispanics had similar disease characteristics and therefore probably the same disease. Further genetic and environmental studies are needed to understand the patterns of Hispanic agespecific incidence rates.