Study Protocol for the Initial Choice of DPP-4 Inhibitor in Japanese Patients with Type 2 diabetes Mellitus: Effect of Linagliptin on QOL (INTEL-QOL) Trial

INTRODUCTION: Consideration of treatment-related quality of life (QOL) is important in diabetes management. However, no studies have compared the influence of dipeptidyl peptidase-4 inhibitors versus metformin on treatment-related QOL when used as first-line therapy in patients with type 2 diabetes mellitus. METHODS: This study is a prospective, randomized, open-label, multicenter, parallel-group, comparative study. Between June 2016 and December 2017, 44 participants who failed to achieve glycemic control despite diet and exercise therapy were recruited at 14 clinics and randomly allocated to linagliptin or metformin therapy. Treatment-related QOL was assessed with the Oral Hypoglycemic Agent Questionnaire, version 2 (OHA-Q ver. 2) and the self-administered Diabetes Therapy-Related QOL (DTR-QOL) questionnaire. The primary study outcome is the difference in total OHA-Q ver. 2 score between the two treatment groups at the end of the study. The secondary outcomes include differences in the scores for each OHA-Q ver. 2 subscale between the two treatment groups at the end of the study, change in total DTR-QOL score and for each domain from baseline to the end of treatment, changes in glycemic control, and adverse events. PLANNED OUTCOME: The present study is designed to assess the effects of linagliptin on the treatment-related QOL. Results will be available in the near future. Study findings are expected to provide useful information on how to maintain or improve QOL in patients with type 2 diabetes mellitus treated with insulin. FUNDING: Nippon Boehringer Ingelheim Co., Ltd. and Eli Lilly and Company. CLINICAL TRIAL REGISTRATION: UMIN000022953.