Differential Treatment Response to Insulin Intensification Therapy: A Post Hoc Analysis of a Randomized Trial Comparing Premixed and Basal-Bolus Insulin Regimens

Introduction: Identification of subgroups of patients that may benefit most from certain treatment is important because individual treatment response varies due to multiple contributing factors. The present study used the subgroup identification based on the differential effect search (SIDES) algorithm to identify subgroups with different treatment responses to insulin intensification therapies. Methods: This was a post hoc analysis of a 24-week, multicenter, open-label, randomized, parallel study comparing prandial premixed therapy (PPT) to basal-bolus therapy (BBT). Patients with type 2 diabetes mellitus were randomized to PPT (insulin lispro mix 50/50 thrice daily with meals) or BBT (glargine at bedtime plus mealtime insulin lispro) insulin intensification therapies. The SIDES algorithm was used to identify the subgroups from at-goal patients [glycated hemoglobin (HbA1c) < 7.0% (53.0 mmol/mol) at the end of 24 weeks; n = 182] who could have benefitted from insulin intensification therapies. Results: Baseline characteristics of overall at-goal patients were comparable between PPT and BBT groups. The SIDES algorithm identified patients with race other than Caucasian (i.e., African-American, Asian, and Hispanic) and baseline fasting blood glucose (FBG) < 8.89 mmol/L as a subgroup that could respond better to PPT relative to BBT than the overall at-goal patient population. In this identified subgroup population, the HbA1c mean (standard deviation) changes from baseline to endpoint in PPT and BBT groups were -2.27 (0.88)% versus -2.05 (0.75)%; p = 0.40, respectively; while in the overall at-goal patients, the HbA1c changes were -2.17 (0.79)% versus -2.34 (1.00)%; p = 0.19, respectively. Conclusions: The preliminary results showed that the subgroup of patients with race other than Caucasian and FBG < 8.89 mmol/L may respond better to premixed intensification therapy. This result provides some preliminary information for further investigation in prospective studies.