1824 DIABETES CARE, VOLUME 21, NUMBER 11, NOVEMBER 1998 I t has been suggested that diabetes is more diverse in its etiology and patho- genesis in black children and adolescents than in young whites. Apart from classic IDDM, other atypical presentations have been described among blacks. These include a syndrome initially named matu- rity-onset diabetes of the young (1) and an atypical form of nonprogressive, nonau- toimmune diabetes, which has an acute onset, is insulin requiring at diagnosis, and displays modest insulinopenia and episodic ketosis (2). Another form was initially described in Jamaica and was characterized by being ketosis-resistant, displaying pha- sic insulin dependence, and being associ- ated with malnutrition (3). Furthermore, a more recent study described the presence of ketosis in black adolescents diagnosed with NIDDM (4). Several studies have reported differ- ences in incidence of IDDM between whites and blacks living in a same area (5–9). Although data on immunologic markers in white patients at onset of IDDM are available from several studies (10–12), including population-based registries in Finland (13,14), Sweden (15), and Bel- gium (16), to our knowledge, there are only few small and/or nonrepresentative studies that have examined these charac- teristics in black patients. Two reports from the 1980s suggested a lower prevalence of islet cell antibodies (ICA) in blacks when compared with whites (17,18). Another early study showed no ICA in sera from black Jamaicans with IDDM of varying duration (19). Two more recent, small stud- ies, one from Pittsburgh (20) and another from Africa (21), reported that the preva- lence of ICA in blacks was similar to that in whites. No study has examined IA-2 AA and only one report, to our knowledge, evaluated the prevalence of antibodies to GAD65 in blacks. This study, from Ten- nessee, found the frequency of GAD65 AA comparable to that in Caucasians, whereas the frequency of ICA was reduced (22). The objective of the current study is to compare the frequency of ICA, GAD65, and IA-2 AA between black and white chil- dren and adolescents at the time of diagno- sis of IDDM and evaluate the relationship of sex, race, and age at onset of IDDM to the frequency of the different antibodies in a large consecutive series of cases from Chil- dren’s Hospital of Pittsburgh. RESEARCH DESIGN AND METHODS Subjects From January 1983 to December 1985, January to December 1989, and January 1996 to December 1997, all consecutive newly diagnosed IDDM patients admitted to Children’s Hospital of Pittsburgh were asked to participate in an ongoing study since 1979. These years were selected for analysis because they are the years before and during increased incidence of IDDM (9). There is no evidence of any trend of a change in the prevalence of autoantibodies during these years. The criteria for inclusion From the Division of Pediatric Endocrinology (I.M.L., D.B.), Department of Pediatrics, and the Division of Immunogenetics (M.P., M.T.), Rangos Research Center, Children’s Hospital of Pittsburgh; and the Diabetes Research Center (I.M.L., J.S.D., R.E.L.), Department of Epidemiology, Graduate School of Public Health, Uni- versity of Pittsburgh, Pittsburgh, Pennsylvania. Address correspondence and reprint requests to Ingrid M. Libman, MD, PhD, Diabetes Research Center, Rangos Research Center, 5th floor, 3460 Fifth Ave., Pittsburgh, PA 15213. E-mail: iml1@vms.cis.pitt.edu. Received for publication 23 February 1998 and accepted in revised form 10 July 1998. Abbreviations: CV, coefficient of variation; H, human blood group 0; ICA, islet cell antibodies; GAD65 AA, autoantibodies against the 65-kDa isoform of GAD; IA-2 (ICA512) AA, IA-2 autoantibodies; JDF, Juve- nile Diabetes Foundation; R, cafeteria fed rat. A table elsewhere in this issue shows conventional and Système International (SI) units and conversion factors for many substances. Islet Cell Autoimmunity in White and Black Children and Adolescents With IDDM O R I G I N A L A R T I C L E OBJECTIVE — To compare the frequency of islet cell antibodies (ICA) and antibodies to GAD65 and IA-2 (ICA512) between black and white children and adolescents at the diagno- sis of IDDM in a large consecutive series of cases from Children’s Hospital of Pittsburgh. RESEARCH DESIGN AND METHODS — ICA and antibodies to GAD65 and IA-2 were measured in 437 white and black children and adolescents who were diagnosed with IDDM at 19 years of age at Children’s Hospital of Pittsburgh from January 1983 to Decem- ber 1985, from January to December 1989, and from January 1996 to December 1997. RESULTS — The prevalence of ICA(H), GAD65, and IA-2 antibodies was significantly lower in blacks than whites at onset of the disease. In contrast, the prevalence of ICA(R) alone was higher in blacks. None of the antibodies were present in 12% of the blacks compared with 4% in whites. The same pattern was seen in both sexes. The prevalence of antibodies in white patients with onset of IDDM at 11 years of age was no different than in those who developed IDDM during adolescence. In contrast, black patients showed a significantly lower prevalence of almost all antibodies in the adolescent group. CONCLUSIONS — Black adolescents were more likely to not have antibodies, suggesting either that they have a nonautoimmune type of diabetes or that antibodies are not being detected by these assays. Diabetes Care 21:1824–1827, 1998 INGRID M. LIBMAN, MD, PHD MASSIMO PIETROPAOLO, MD MASSIMO TRUCCO, MD JANICE S. DORMAN, PHD RONALD E. LAPORTE, PHD DOROTHY BECKER, MBBCH, FCP Epidemiology/Health Services/Psychosocial Research