Study design of the Fasting In diabetes Treatment (FIT) trial: a randomised, controlled, assessor blinded intervention trial which examines the effect of intermittent use of a fasting mimicking diet in patients with type 2 diabetes

Background Caloric restriction is an effective way to treat type 2 diabetes (DM2). However, chronic restriction of food intake is difficult to sustain. Intermittent total fasting exerts similar metabolic effects, but may be even more challenging for most patients. A fasting mimicking diet (FMD) was designed to achieve the metabolic benefits of total fasting, despite considerable calorie content. The effects of a FMD in DM2 patients are still unknown.

Aim To determine the effect of intermittent use (5 consecutive days a month during a year) of a FMD in DM2 patients on metabolic parameters and DM2 medication use compared to usual care.

Method One hundred DM2 patients from general practices in the Netherlands with a BMI ≥ 27 kg/m², treated with lifestyle advice only or metformin, will be randomised to receive the FMD plus usual care or usual care only. Primary outcomes are HbA1c and DM2 medication dosage. Secondary outcomes are anthropometrics, blood pressure, plasma lipid profiles, quality of life, treatment satisfaction, metabolomics, microbiome, MRI (for example, cardiac function and fat distribution), cost-effectiveness, and feasibility in clinical practice.

Results The first 70 patients are included. Follow up will be completed in April 2021.

Conclusion Our results will show whether monthly cycles of a FMD are feasible in clinical practice, if they improve metabolic parameters and/or reduce the need for medication in DM2 and if this is a cost-effective intervention.