To investigate the prevalence of adult-onset insulin-dependent diabetes mellitus (IDDM) in a nationally representative sample of adults 30–74 years of age. Although it is a widely held belief that onset of IDDM in adults is rare, there are few objective data to support this. Adult-onset IDDM may represent a disease that is biologically distinct from youth-onset IDDM, and it would be important to distinguish these two entities.


The Second National Health and Nutrition Examination Survey (NHANES II) contained a national probability sample of 12,102 subjects 30–74 years of age in the U.S. population. All subjects with diabetes diagnosed by a physician before the survey were identified. Cases of IDDM defined by age at diagnosis ≥ 30 years, continuous or nearly continuous insulin treatment since diagnosis of diabetes, and relative body weight ≤ 125 were classified as adult-onset IDDM.


Subjects with adult-onset IDDM represented 0.30% of the U.S. population 30–74 years of age and 7.4% of all diabetic patients diagnosed at 30–74 years of age.


These data indicate that onset of IDDM in adults is uncommon. Given the limitations of the survey instrument, subclinical or slowly progressive IDDM (as distinguished from non-insulin-dependent diabetes mellitus with progressive loss of β-cell function) would not have been detected, and these would constitute additional cases of adult-onset IDDM. However, the data suggest that a very large population base would be required to identify sufficient numbers of adult-onset IDDM cases for study of the etiology and pathogenesis of this disease.

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