Efficacy of time-restricted eating and behavioural economic interventions in reducing fasting plasma glucose, HbA1c and cardiometabolic risk factors compared with time-restricted eating alone or usual care in patients with impaired fasting glucose: protocol for an open-label randomised controlled trial.

Introduction: Impaired fasting glucose (IFG) is a significant risk factor for diabetes mellitus. Time-restricted eating (TRE) is one type of diet showing positive effects on metabolic signal pathways. However, effects of TRE on cardiometabolic risk factors in humans are limited. Additionally, compliance with TRE remains problematic despite having intention to follow the diet control. Therefore, this study aims to investigate the efficacy of TRE with behavioural economic interventions or TRE alone relative to usual care, in reducing fasting plasma glucose (FPG), haemoglobin A1c (HbA1c) and other cardiometabolic risk factors in patients with IFG.

Methods And Analysis: This parallel-group, open-label randomised controlled trial will be conducted at the outpatient clinic of the Department of Family Medicine, Faculty of Medicine, Ramathibodi Hospital, Bangkok, Thailand. Patients aged 18-65 years with IFG defined as FPG 100-125 mg/dL and body mass index ≥25 kg/m will be recruited between October 2021 and October 2022. Patients will be randomly allocated to three groups (1:1:1 ratio) as (1) TRE with behavioural economic interventions including financial incentives and text reminders, (2) TRE alone or (3) usual care. The number of participants will be 38 per group (a total of 114). The duration of the intervention will be 12 weeks. Primary outcome is FPG levels measured at 12 weeks after randomisation. Secondary outcomes are HbA1c, body weight, systolic and diastolic blood pressure, fasting insulin, serum triglyceride, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol and high-sensitivity C reactive protein. P value of <0.05 of two-sided test will be considered as statistical significance.

Ethics And Dissemination: The study protocol has been approved by the Ethics Committee of the Faculty of Medicine, Ramathibodi Hospital, Mahidol University (MURA2021/389). All patients will be informed about the details of the study and sign written informed consent before enrollment in the study. Results from this study will be published in a peer-reviewed journal.

Trial Registration Number: TCTR20210520002.