Type 1 Diabetes Mellitus in the First Years of Life - Onset, Initial Treatment, and Early Disease Course

Objective This study investigated the onset and the choice of treatment in children with very early onset of type 1 diabetes mellitus (T1D). Methods The study included 5,763 patients from the German Diabetes Patient Follow-up registry with onset of T1D in the first 4 years of life from January 2010 - June 2022. The analysis included diabetes-specific parameters, anthropometric data, and mode of treatment at onset, within the first and second year of T1D. Three groups were compared according to age at onset (G1: 223 patients 6-<12 months, G2: 1519 patients 12-<24 months, G3: 4001 patients 24-48 months). Results In 12.3% of all cases in childhood and adolescence, the incidence of diabetes in the first 4 years of life was rare. At the onset, clinical status was worse and diabetic ketoacidosis (DKA) rates were higher in G1 and G2 (52.3% and 46.5%, respectively) compared to G3 (27.3% (p<0.001)). G1 and G2 were significantly more likely to be treated with insulin pump therapy (CSII) 2 years after onset (98.1% and 94.1%, respectively)) compared to G3 (85.8%, p<0.001). Median HbA1c after 2 years did not differ between groups (G1: 7.27% (56.0 mmol/mol), G2: 7.34% (56.7 mmol/mol) and G3: 7.27% (56.0 mmol/mol)) or when comparing CSII vs MDI. The rate of severe hypoglycemia (SH) and DKA during the first 2 years of treatment did not differ among the three groups, ranging from 1.83-2.63/100 patient-years (PY) for DKA and 9.37-24.2/100 PY for SH. Children with T1D under 4 years of age are more likely to be diagnosed with celiac disease but less likely to have thyroiditis than older children with T1DM. Conclusions Young children with T1D had high rates of DKA at onset and were predominantly treated with insulin pump therapy during the first 2 years. The median HbA1c for all three groups was<7.5% (58 mmol/mol) without increased risk of SH or DKA. The use of continuous glucose monitoring (CGM) was not associated with lower HbA1c in children under 48 months.