title: Familial and sporadic insulin-dependent diabetes: evidence for heterogeneous etiologies?
abstract: Heterogeneity within insulin-dependent diabetes mellitus (IDDM) has been hypothesized, but few studies have focused on differences which may exist between familial and sporadic IDDM cases. Presenting characteristics for 330 white, newly diagnosed IDDM cases were evaluated. Familial cases were older (10.2 +/- 5.1 years vs 7.9 +/- 4.2 years, P = 0.010) and had, on average, less severe metabolic disturbances at presentation, as demonstrated by lower mean hemoglobin A1 (12.6 +/- 2.4% vs 14.4 +/- 2.6%, P = 0.001) and mean insulin dose at discharge (0.62 +/- 0.35 U/kg/day vs 0.85 +/- 0.29 U/kg/day, P less than 0.001), and higher mean plasma bicarbonate concentrations (19.3 +/- 3.9 mmol/l vs 15.8 +/- 5.9 mmol/l, P = 0.023) and mean plasma C-peptide levels (0.35 +/- 0.36 pmol/ml vs 0.14 +/- 0.15 pmol/ml, P less than 0.001). Further analyses on a subset of IDDM cases (n = 100) indicated that initial differences in metabolic indices observed at diagnosis were no longer apparent at one-year post-diagnosis. These results suggest that the etiology of familial and sporadic IDDM is similar and that the less severe presentation observed at diagnosis in the familial cases may be due to earlier identification of the disease, reflecting increased parental knowledge of diabetic symptoms and/or frequent testing for diabetes.
authors.affiliation: Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pennsylvania 15261.
authors.forename: L A
authors.initials: LA
authors.lastname: O'Leary
authors.forename: J S
authors.initials: JS
authors.lastname: Dorman
authors.forename: R E
authors.initials: RE
authors.lastname: LaPorte
authors.forename: T J
authors.initials: TJ
authors.lastname: Orchard
authors.forename: D J
authors.initials: DJ
authors.lastname: Becker
authors.forename: L H
authors.initials: LH
authors.lastname: Kuller
authors.forename: M S
authors.initials: MS
authors.lastname: Eberhardt
authors.forename: D E
authors.initials: DE
authors.lastname: Cavender
authors.forename: B S
authors.initials: BS
authors.lastname: Rabin
authors.forename: A L
authors.initials: AL
authors.lastname: Drash
mesh_terms: D000367:Age Factors; D001323:Autoantibodies / Q000032:analysis; D002648:Child; D003922:Diabetes Mellitus, Type 1 / Q000209:etiology* / Q000235:genetics* / Q000503:physiopathology; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis; D006684:HLA-DR Antigens / Q000032:analysis; D006801:Humans; D007515:Islets of Langerhans / Q000276:immunology; D008297:Male; D012621:Seasons; D012727:Sex Characteristics
chemical_list: D001323:Autoantibodies; D006442:Glycated Hemoglobin; D006684:HLA-DR Antigens; C024211:islet cell antibody