Protocol for a 1-year randomised, controlled, parallel group, open-label trial on the effects and feasibility of time-restricted eating in individuals with type 2 diabetes- The Restricted Eating Time in the Treatment of Type 2 Diabetes (RESET2) trial

Aim: Time-restricted eating (TRE) limits the time for food intake to typically 6–10 h/day without other dietary restrictions. The aim of the RESET2 (the REStricted Eating Time in the treatment of type 2 diabetes) trial is to investigate the effects on glycaemic control (HbA_1c) and the feasibility of a 1-year TRE intervention in individuals with overweight/obesity and type 2 diabetes. The aim of the present paper is to describe the protocol for the RESET2 trial. Methods: RESET2 is a randomised, controlled, parallel-group, open-label trial. One hundred and sixty individuals with type 2 diabetes (HbA_1c >53 mmol/mol (>7.0%)), and Body Mass Index ≥25 kg/m² will be randomised to standard care plus TRE, or to standard care and habitual living. Both the intervention and control group will follow standard diabetes care including regular clinical visits 3–4 times/year. The intervention is divided into two periods: (1) a 3-month TRE period with a fixed eating window with a self-selected timing to obtain data from the participants' experiences with TRE and (2) a 9-month individually adjusted TRE period. Participants in the TRE group will be instructed to reduce their eating window by a minimum of 3 h/day compared to the habitual eating window and with an eating window of 8–10 h/day. Test days will be scheduled at baseline, after 3 months and after 1 year. The primary outcome is HbA_1c (evaluated 3 months and 1 year after randomisation) and secondary outcomes are body weight, fat mass, continuous glucose monitoring derived time-in-range and use of antidiabetic medicine (evaluated 1 year after randomisation). Additionally, we will conduct a process evaluation to assess whether the TRE intervention functioned as hypothesised.