ObjectiveTo explore whether children diagnosed with type 1 diabetes during islet autoantibody surveillance through The Environmental Determinants of Diabetes in the Young (TEDDY) study retain greater islet function than children diagnosed through the community. Methods TEDDY children identified at birth with high-risk human leukocyte antigen and followed every 3months until diabetes diagnosis were compared to age-matched children diagnosed with diabetes in the community. Both participated in long-term follow up after diagnosis. Hemoglobin A1c (HbA1c) and mixed meal tolerance test were performed within 1month of diabetes onset, then at 3, 6, and 12months, and biannually thereafter. ResultsComparison of 43 TEDDY and 43 paired control children showed that TEDDY children often had no symptoms (58%) at diagnosis and none had diabetic ketoacidosis (DKA) compared with 98% with diabetes symptoms and 14% DKA in the controls (P<0.001 and P=0.03, respectively). At diagnosis, mean HbA1c was lower in TEDDY (6.8%, 51mmol/mol) than control (10.5%, 91mmol/mol) children (P<0.0001). TEDDY children had significantly higher area under the curve and peak C-peptide values than the community controls throughout the first year postdiagnosis. Total insulin dose and insulin dose-adjusted A1c were lower throughout the first year postdiagnosis for TEDDY compared with control children. ConclusionsHigher C-peptide levels in TEDDY vs community-diagnosed children persist for at least 12months following diabetes onset and appear to represent a shift in the disease process of about 6months. Symptom-free diagnosis, reduction of DKA, and the potential for immune intervention with increased baseline C-peptide may portend additional long-term benefits of early diagnosis.