Introduction: Autoimmune diabetes in adults comprises a broad spectrum of clinical phenotypes.
Objectives: The aim of the study was to investigate clinical and biochemical features and anti-islet autoantibody pattern in adult patients with newly diagnosed autoimmune diabetes with regard to age and the number of autoantibodies detected at diagnosis.
Patients and methods: We retrospectively evaluated 344 patients (aged ≥18 years) with newly diagnosed diabetes and a positive anti-islet antibody titer. Patients were divided based on age (<35 and ≥35 years of age) or the number of detected autoantibodies (1, 2, or 3).
Results: The studied age groups did not differ with respect to the majority of clinical and laboratory features (e.g., clinical presentation, metabolic status, or degree of insulin deficiency). Autoantibodies to islet cell cytoplasm and to glutamic acid decarboxylase 65 occurred more frequently in younger patients, while the prevalence of autoantibodies to intracytoplasmatic domain of the tyrosine phosphatase-like protein (IA-2A) was similar in both age groups. Single autoantibody positivity was observed more often in older patients. The most common isolated autoantibody in this group was IA-2A. The presence of multiple autoantibodies was associated with younger age, lower fasting and stimulated C-peptide levels, and shorter duration of symptoms.
Conclusions: The patient's age at diabetes onset does not determine clinical and biochemical characteristics at diagnosis but is associated with different autoantibody status. IA-2A antibodies may be useful in diagnosing autoimmune diabetes in adult patients. The assessment of the immune profile at diagnosis may help identify patients at a higher risk of significant insulin deficiency.