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) 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 >53 mmol/mol (>7.0%)), and Body Mass Index ≥25 kg/m 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 (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.