Combination of disease duration‐to‐age at diagnosis and hemoglobin A1c‐to‐serum C‐peptide reactivity ratios predicts patient response to glucose‐lowering medication in type 2 diabetes: A retrospective cohort study across Japan (JDDM59)

AIMS/INTRODUCTION: Knowing the collective clinical factors that determine patient response to glucose‐lowering medication would be beneficial in the treatment of type 2 diabetes. We carried out a retrospective cohort study to explore the combination of clinical factors involved in its therapeutic efficacy. MATERIALS AND METHODS: The results of cohort studies retrieved using the CoDiC(®) database across Japan from January 2005 to July 2018 were analyzed based on criterion that using insulin therapy indicates severe type 2 diabetes. RESULTS: A logistic regression analysis showed that age at diagnosis, disease duration, hemoglobin A1c (HbA1c) and serum C‐peptide reactivity (CPR) at medication commencement were associated with the probability of insulin treatment. Receiver operating characteristic curve showed that these clinical factors predicted insulin treatment positivity with an area under the curve of >0.600. The area under the curve increased to 0.674 and 0.720 for the disease duration‐to‐age at diagnosis ratio and HbA1c‐to‐CPR ratio, respectively. Furthermore, area under the curve increased to 0.727 and 0.750 in the indices (duration‐to‐age ratio at diagnosis × 43 + HbA1c) and (duration‐to‐age ration at diagnosis × 21 + HbA1c‐to‐CPR ratio), respectively. After stratification to three groups according to the indices, monthly HbA1c levels during 6 months of treatment were higher in the upper one‐third than in the lower one‐third of patients, and many patients did not achieve the target HbA1c level (53 mmol/mol) in the upper one‐third, although greater than fourfold more patients were administered insulin in the upper one‐third. CONCLUSIONS: The combination of disease duration‐to‐age at diagnosis and HbA1c‐to‐CPR ratios is a collective risk factor that predicts response to the medications.