Prevalence of diabetes mellitus and impaired glucose tolerance among second-generation Japanese-American men

Abstract

We describe the initial findings from a multidisciplinary, epidemiologic study of diabetes mellitus conducted in a population of secondgeneration Japanese-American (Nisei) men born between 1910 and 1939 who reside in King County, Washington ( n = 1746). From this study population, 487 volunteered, and 229 were enrolled to comprise the study sample. A random sample of Nisei men was also drawn from the population to develop a reference sample of 189 men. All subjects participated in a 75-g oral glucose tolerance test; the National Diabetes Data Group (NDDG) and World Health Organization (WHO) diagnostic criteria as well as a modification of the WHO criteria were used to classify individuals with normal glucose tolerance, impaired glucose tolerance (IGT), or diabetes. Within the study sample, 79 men were found to have normal glucose tolerance, 72 had IGT, and 78 had type II diabetes. The mean age of the study sample was 61.4 yr. Based on comparison of the study sample to the reference sample, the study sample was ascertained to be representative of Nisei men in King County. Extrapolating from our observations in the reference sample and in the study sample, we have estimated that ∼56% of Nisei men in the study population have abnormal glucose tolerance. Much of this is undiagnosed because only ∼13% of the reference sample of Nisei men reported a prior diagnosis of diabetes. Of the men who enrolled in the study as nondiabetic subjects, 11.1% had diabetes and 39.2% had IGT; i.e., 50.3% had previously unknown abnormalities in glucose tolerance. We estimate that ∼20% of Nisei men have diabetes (both previously diagnosed and undiagnosed) and ∼36% have IGT.