Influence of sex and age at onset on autoantibodies against insulin, GAD(65) and IA2 in recent onset type 1 diabetic patients

Autoantibodies against insulin (IAA), glutamic acid decarboxylase (GADA) an d tyrosine phosphatase IA2 (IA2A) were measured in sera from 448 recent ons et patients with type 1 diabetes mellitus (DM) subdivided according to sex (194 female and 254 male) and age at onset (134 patients diagnosed before 1 0 years, 187 between 10 and 20 years, 66 between 20 and 30 years and 61 ove r 30 years. Results: Autoantibodies were more frequent in female DM patient s (93.8 vs. 86.6%, p = 0.013) due to an increased prevalence of both GADA ( 86.1 vs. 70.1%) and IA2A (59.3 vs. 49.2%), with GADA levels also significan tly higher in women (0.24 vs. 0.18 U, p = 0.0003). When age groups were com pared, there was a reduction in prevalence in patients over 20 years for bo th IAA (70% for patients diagnosed under 20 and 36% for older patients) and IA2A (65 and 25%, respectively). These differences also affected IAA level s, with the highest antibody titres in the youngest group (1,214.1 nU/ml in children under 10 compared to 546.9, 345.6 and 341.1 nU/ml in the subseque nt groups; p < 10(-4)). GADA prevalence did not differ significantly betwee n age groups but, nevertheless, autoantibody levels were highest among the oldest type 1 DM patients (0.327 U compared to 0.216, 0.197 and 0.176 U in the decreasing age groups; p < 10(-4)). Conclusion: There are sex- and age- related differences affecting the presence and/or titres of P cell autoanti bodies. We speculate that these differences could reflect the severity and specificity of the autoimmune attack against the endocrine pancreas and mig ht influence the rate of progression to type 1 DM or the risk of developing other autoimmune diseases. Copyright (C) 2001 S. Karger AG. Basel.