Partial remission definition: validation based on the insulin dose-adjusted HbA1c (IDAA1C) in 129 Danish children with new-onset type 1 diabetes.

Objective: To validate the partial remission (PR) definition based on insulin dose-adjusted HbA1c (IDAA1c). Subjects and methods: The IDAA1c was developed using data in 251 children from the European Hvidoere cohort. For validation, 129 children from a Danish cohort were followed from the onset of type 1 diabetes (T1D). Receiver operating characteristic curve (ROC) analysis was used to evaluate the predictive value of IDAA1c and age on partial C-peptide remission (stimulated C-peptide, SCP> 300 pmol/L). Results: PR (IDAA1c <= 9) in the Danish and Hvidoere cohorts occurred in 62 vs. 61% (3 months, p=0.80), 47 vs. 44% (6 months, p=0.57), 26 vs. 32% (9 months, p= 0.32) and 19 vs. 18% (12 months, p= 0.69). The effect of age on SCP was significantly higher in the Danish cohort compared with the Hvidoere cohort (p< 0.0001), likely due to higher attained Boost SCP, so the sensitivity and specificity of those in PR by IDAA1c <= 9, SCP>300 pmol/L was 0.85 and 0.62 at 6 months and 0.62 vs. 0.38 at 12 months, respectively. IDAA1c with age significantly improved the ROC analyses and the AUC reached 0.89 +/- 0.04 (age) vs. 0.94 +/- 0.02 (age+ IDAA1c) at 6 months (p< 0.0004) and 0.76 +/- 0.04 (age) vs. 0.90 +/- 0.03 (age+ IDAA1c) at 12 months (p< 0.0001). Conclusions: The diagnostic and prognostic power of the IDAA1c measure is kept but due to the higher Boost stimulation in the Danish cohort, the specificity of the formula is lower with the chosen limits for SCP (300 pmol/L) and IDAA1c <= 9, respectively.