Low fasting glucose‐to‐estimated average glucose ratio was associated with superior response to insulin degludec/aspart compared with basal insulin in patients with type 2 diabetes

AIMS/INTRODUCTION: The benefits of once‐daily insulin degludec/aspart (IDegAsp) compared with basal insulin in type 2 diabetes patients have not been established. MATERIALS AND METHODS: This was a retrospective observational study. From a basal insulin cohort from three referral hospitals, patients were enrolled who initiated once‐daily IDegAsp. A control group maintaining basal insulin was selected by propensity score matching. Glycated hemoglobin (HbA1c) changes over a period of 6 months and associated clinical factors were evaluated. RESULTS: The IDegAsp group and the control group comprised of 87 patients, respectively. Baseline HbA1c was comparable between the two groups (8.7 ± 0.9 vs 8.6 ± 0.9%, mean and standard deviation). After 6 months with matched insulin doses, HbA1c in the IDegAsp group was lower than that in the control group (8.1 ± 1.0 vs 8.4 ± 1.1%, P = 0.029). Among baseline variables, fasting plasma glucose (FPG) and fasting C‐peptide in the IDegAsp were lower than that in the control (FPG 124.2 ± 38.4 vs 148.0 ± 50.6 mg/dL, P < 0.001). Considering that the lower FPG despite the comparable HbA1c could be related with the efficacy of IDegAsp, subgroup analysis was carried out according to a ratio of FPG‐to‐estimated average glucose, which is calculated from HbA1c. When compared with each control group, the superiority of IDegAsp in the reduction of HbA1c was significant only in the patients with a lower FPG‐to‐estimated average glucose ratio (0.49 ± 0.09), but not in those with a higher FPG‐to‐estimated average glucose ratio (0.79 ± 0.20). CONCLUSIONS: We observed that IDegAsp was more effective than basal insulin in patients with an FPG lower than predicted by HbA1c, which might be related with insulin deficiency and postprandial hyperglycemia in patients on basal insulin therapy.