HYPERINSULINEMIA AND ACANTHOSIS NIGRICANS IN AFRICAN-AMERICANS

Compared with the US white, non-Hispanic population, the African-Ameri can population has a nearly two-fold higher prevalence of noninsulin-d ependent diabetes mellitus (NIDDM). Obesity, which usually precedes NI DDM, is associated with the skin lesion acanthosis nigricans in Africa n Americans. This study was undertaken to determine what the relations hip of acanthosis nigricans was to hyperinsulinemia, a major risk fact or for NIDDM. Eighty-nine African-American subjects with acanthosis ni gricans and 25 others without the skin lesion were evaluated using ora l glucose tolerance testing and responsiveness to insulin. Noninsulin- dependent diabetes mellitus was present in 19 of the subjects with aca nthosis nigricans. The prevalence of NIDDM in this group increased wit h increasing age, reaching 50% among those in their 40s. Fasting plasm a insulin concentration was in direct proportion to the severity of th e acanthosis nigricans involvement of the neck. These data suggest tha t among African Americans, this skin lesion is a marker for hyperinsul inemia and insulin resistance. Furthermore, the presence of acanthosis nigricans identifies a subset with a much higher prevalence of NIDDM than is present in African Americans in the general population.