Children with type 1 diabetes of early age at onset - immune and metabolic phenotypes.

Objectives We aimed to evaluate children with type 1 diabetes (T1D) with early age at onset (EAO) for clinical, immune and metabolic features in order to identify age-related disease phenotypes. Methods Comparative study of two groups of T1D children: EAO (≤5 years) and later age at onset (LAO; >5 years), regarding the presence of other autoimmune (AI) diseases, diabetes ketoacidosis and immunologic profile at onset and metabolic data 1 year after diagnosis. Statistical analysis was performed with significance set for p < 0.05. Results The study included 137 children (EAO = 52, mean age 3.6 ± 1.5 [mean ± standard deviation (SD)] and LAO = 85, mean age 10.4 ± 2.9). EAO was more associated with concomitant AI diseases (p = 0.032). Despite no differences in disease onset, EAO presented with lower C-peptide levels (p = 0.01) and higher absolute lymphocyte number (p < 0.0001), with an inverse correlation between these two variables (p = 0.028). Additionally, the EAO group had a higher frequency of serum detection of three antibodies (Abs) (p = 0.0008), specifically insulin Abs (p = 0.0001). One year after diagnosis, EAO had higher total daily insulin (TDI) dose (p = 0.008), despite similar hemoglobin A1c (HbA1c). Conclusions Our data show an association of EAO T1D with more AI diseases, higher number of Abs, lower initial insulin reservoir and higher insulin requirements 1 year after diagnosis. In this group, immune imbalance seems more evident and disease progression faster, probably reflecting distinct "immune environment" with different ages at disease onset. Further studies in the field of immunogenetics and immune tolerance are required, to improve patient stratification and find novel targets for therapeutic intervention.