Reply to the comment of Wilbrink et al. on Retrospective analysis of liraglutide and basal insulin combination therapy in Japanese type 2 diabetes: The association between remaining β‐cell function and the achievement of the HbA1c target 1 year after initiation

We have reported that the HbA1c‐lowering effects of liraglutide/basal insulin combination rely on remaining β‐cell function and that the cut‐off value of the C‐peptide immunoreactivity index (CPI), a β‐cell function‐related index frequently used in Japanese clinical settings, is 1.103 for the achievement of HbA1c <7.0% at 54 weeks after initiating the liraglutide/basal insulin combination. Wilbrink et al claimed that glucose‐lowering effects of glucagon‐like peptide‐1 receptor agonist liraglutide depend of duration of type 2 diabetes; while our resent study published in the Journal of Diabetes Investigation failed to detect such dependency. This discrepancy might be due to several reasons including co‐administration of basal insulin with liraglutide in our study; ethnic difference in T2D pathophysiology between the two study; and difference in sample size (The Usui study on liraglutide/basal insulin, n = 38; the Usui study on liraglutide monotherapy or SU combination, n=88; and the Wilbrink study, n = 69).[Image: see text]