Effect of early versus late time-restricted eating on glycaemic control, measured by continuous glucose monitoring, in adults at risk for type 2 diabetes
Aim: To investigate via the use of continuous glucose monitors (CGM) the acute effect of time-restricted eating (TRE) in early (eTRE; 8:00-16:00 hrs) versus late (lTRE; 12:00-20:00 hrs) conditions on inter-day glycaemic variability (GV) in adults at risk for type 2 diabetes (T2D).
Methods: Eight sedentary individuals (five female/ three male; 51±6 years; body mass index (BMI) 28.0±2.9 kg/m2; Glycated haemoglobin (HbA1c) 37.9±3.3 mmol/mol) with a habitual food intake distribution >14 hrs/day, participated in a randomised-crossover control TRE study. Protocol compared eTRE to lTRE as well as non-TRE to TRE periods, with each phase lasting 3-days. TRE conditions utilised were isocaloric and eucaloric, and energy intake was calculated via Mifflin-St Jeor equation. Meals provided within the TRE condition consisted of 60% CHO, 25% protein, and 16% fat. CGM was used to assess markers of GV, including but not exclusive to mean absolute glucose (MAG), coefficient of variation (CV), and mean amplitude of glycaemic excursions (MAGE). A 2 factor repeated measures analysis of variance was used (2 conditions [eTRE vs lTRE] x 2 time-points [baseline vs TRE]) for statistical testing. Results: Following TRE, a significant reduction, was observed within MAG by 0.4 mmol/l (95% CI 0.1 to 0.8; 0.041), MAGE by 0.4 mmol/l (95% CI 0.1 to 0.8; P= 0.024) and CV by 2.5 mmol/l (0.6, 4.4) p values 0.041, 0.024, 0.016 respectively (i.e., baseline to TRE). There were no significant changes in physical activity (PA) or diet (total caloric intake, CHO and fat), however protein did significantly differ from baseline to TRE, 21.8g (baseline before eTRE; beTRE) and 23.2g (baseline before lTRE; blTRE) less in comparison to TRE (150g). Conclusion: In the absence of calorie restriction, TRE improved some markers of inter-day GV. This data indicates a possible therapeutic role of TRE in adults at risk for T2D.
Further direction: This small study of short-term TRE provided an understanding for possible effects exhibited by an 8-hour TRE protocol on glycaemic markers. Future studies should determine whether the significant effects are still experienced in the long-term via a longer intervention period. Additionally, a larger, more varied cohort should be utilised analysing various ages, ethnicities, and BMI groups due to the low generalisability of the few current studies available
