Autoimmune Diabetes From Childhood to Adulthood: The Role of Pancreatic Autoantibodies and HLA-DRB1 Genotype

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CONTEXT: Autoimmune diabetes can develop at any age, but unlike early-onset diabetes, adult onset is less well documented. We aimed to compare, over a wide age range, the most reliable predictive biomarkers for this pathology: pancreatic-autoantibodies and HLA-DRB1 genotype. METHODS: A retrospective study of 802 patients with diabetes (aged 11 months to 66 years) was conducted. Pancreatic autoantibodies at diagnosis: insulin autoantibodies (IAA), glutamate decarboxylase autoantibodies (GADA), islet tyrosine phosphatase 2 autoantibodies (IA2A), and zinc transporter-8 autoantibodies (ZnT8A) and HLA-DRB1 genotype were analyzed. RESULTS: Compared with early-onset patients, adults had a lower frequency of multiple autoantibodies, with GADA being the most common. At early onset, IAA was the most frequent in those younger than 6 years and correlated inversely with age; GADA and ZnT8A correlated directly and IA2A remained stable.The absence of HLA-DRB1 risk genotype was associated with higher age at diabetes onset (27.5 years; interquartile range [IQR], 14.3-35.7), whereas the high-risk HLA-DR3/DR4 was significantly more common at lower age (11.9 years; IQR, 7.1-21.6). ZnT8A was associated with DR4/non-DR3 (odds ratio [OR], 1.91; 95% CI, 1.15-3.17), GADA with DR3/non-DR4 (OR, 2.97; 95% CI, 1.55-5.71), and IA2A with DR4/non-DR3 and DR3/DR4 (OR, 3.89; 95% CI, 2.28-6.64, and OR, 3.08; 95% CI, 1.83-5.18, respectively). No association of IAA with HLA-DRB1 was found. CONCLUSION: Autoimmunity and HLA-DRB1 genotype are age-dependent biomarkers. Adult-onset autoimmune diabetes is associated with lower genetic risk and lower immune response to pancreatic islet cells compared with early-onset diabetes.