DIVERGING EVOLUTION OF ANTI-GAD AND ANTI-IA-2 ANTIBODIES IN LONG-STANDING DIABETES-MELLITUS AS A FUNCTION OF AGE AT ONSET - NO ASSOCIATION WITH COMPLICATIONS

Glutamic acid decarboxylase autoantibodies (GAD-A) and tyrosine phosph atase IA-2 autoantibodies (IA2-A) were measured in sera of 50 recently diagnosed (<6 wk, 33 % younger than 15 yr), 19 short-term (1 to 9 yr, 35 % with onset age below 15 yr) and 89 long-standing diabetic patien ts (>10 yr, 57 % with onset age below 15 yr). Complications were asses sed by clinical examination, retinal angiographs and microalbuminuria measurement. Both prevalences and levels of CAD-A and IA2-A decreased with increasing duration of diabetes. However even in those with long duration diabetes, 15 to 63 % of the sera were still positive for one or two antibodies. In the group with onset after the age of 15 yr, sig nificantly higher prevalences and levels of CAD-A (but not IA2-A) was observed in comparison with the group with earlier onset. No associati on was found with any microvascular complications in any group. We con clude that CAD-A and IA2-A persist in some diabetic patients, despite a long duration. Persistence of CAD-A was greatest in those with postp ubertal disease onset. We speculate that persistence of some beta-cell s or specific environmental factors can sustain one autoimmune reactio n especially in some postpubertal-onset diabetic patients. (C) 1998 Jo hn Wiley & Sons, Ltd.