title: Autoantibodies to glutamic acid decarboxylase and insulin in islet cell antibody positive presymptomatic type 1 diabetes mellitus: frequency and segregation by age and gender.
abstract: The frequency of antibodies to glutamic acid decarboxylase (GAD) and insulin (IAA) in presymptomatic Type 1 diabetes mellitus with a positive test for antibodies to islet cell antigen (ICA) was examined. Thirty-two persons positive for ICA (> 10 JDF units) were tested 2 to 48 months before their ascertained onset of Type 1 diabetes. ICA was quantitated by immunofluorescence as JDF units, anti-GAD by radioimmunoprecipitation and anti-insulin by radioimmunoassay. There was a positive test for anti-GAD in 25 (78%), and for IAA in 23 (72%), of the 32 prediabetic ICA-positive subjects. Stratification according to age at the onset of diabetes showed differing frequencies of anti-GAD and IAA in the prediabetic stage. Thus the positivity rate for anti-GAD for 18 subjects older than 10 years at onset of diabetes was 83%, and for 14 aged 10 or younger at onset was 71%; conversely, the rate for IAA for 18 subjects older than 10 at onset was 56% and for 14 aged 10 or less at time of onset was 93% (p = 0.01). The frequency of anti-GAD was higher in females (88%) than males (71%) whereas the frequency of IAA was higher in males (82%) than in females (60%). Since autoantibodies to GAD and insulin occur in presymptomatic Type 1 diabetes with differences in frequencies by age and gender, the stimuli to autoimmunity may operate differently at different ages, and may also be gender-related.
authors.affiliation: International Diabetes Institute, Caulfield General Medical Centre, Victoria, Australia.
authors.forename: P Z
authors.initials: PZ
authors.lastname: Zimmet
authors.forename: R B
authors.initials: RB
authors.lastname: Elliott
authors.forename: I R
authors.initials: IR
authors.lastname: Mackay
authors.forename: T
authors.initials: T
authors.lastname: Tuomi
authors.forename: M J
authors.initials: MJ
authors.lastname: Rowley
authors.forename: C C
authors.initials: CC
authors.lastname: Pilcher
authors.forename: W J
authors.initials: WJ
authors.lastname: Knowles
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D017668:Age of Onset; D001323:Autoantibodies / Q000097:blood*; D002648:Child; D002675:Child, Preschool; D003922:Diabetes Mellitus, Type 1 / Q000175:diagnosis / Q000276:immunology*; D005260:Female; D005968:Glutamate Decarboxylase / Q000276:immunology*; D006801:Humans; D007330:Insulin Antibodies / Q000097:blood*; D007515:Islets of Langerhans / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D017678:Sex Distribution
chemical_list: D001323:Autoantibodies; D007330:Insulin Antibodies; D005968:Glutamate Decarboxylase