Effect of Medium Chain Triglycerides and Whey Protein Isolate Preloads on Glycaemia in Type 2 Diabetes: A randomised crossover study.

Background Small nutritional preloads can reduce postprandial glucose excursions in individuals with and without metabolic syndrome or T2D. However, most studies have focused on preloads administered before single meals and have predominantly used protein-based preloads.Objective To investigate the effects of sequential consumption of medium chain triglycerides (MCT) and whey protein isolate (WPI) preloads before breakfast lunch and dinner on postprandial, diurnal and 24h glycaemia in individuals with T2D.Methods Participants with T2D were studied over three randomised 24-hour periods. They consumed either water before standardised breakfast, lunch and dinner (CONTROL), 15g MCT before breakfast and water before lunch and dinner (MCT), or 15g MCT before breakfast and 10g WPI before lunch and dinner (MCT+WPI). Diurnal (08:00-23:00h) and 24h (08:00-08:00h) glycaemia [incremental area under the curve (iAUC)] and glycaemic variability (%coefficient of variation (%CV)) were evaluated by continuous glucose monitoring (CGM). Postprandial glycaemia (PPG) after breakfast and lunch was assessed by arterialised blood glucose iAUC.Results In 21 enrolled patients (8 males/13 females, mean±SD age 55.1±8.5 yrs, BMI 31.7±4.3 kg·m-2, HbA1c 59±12 mmol·mol-1) diurnal and 24h iAUC were similar across interventions, whereas 24h %CV was lower in MCT (16.8±0.8%, P=0.033) and MCT+WPI (16.1±0.9%, P=0.0004) than CONTROL (18.7±0.9%). PPG iAUC was ∼17% lower after breakfast in MCT and MCT+WPI compared with CONTROL, but only the MCT+WPI lowered glucose by 20% (P=0.002) over the entire day (08:30-17:30h). GIP (P=0.00004), PYY (P=0.01) and β-hydroxybutyrate (P=0.0001) were higher in MCT and MCT+WPI than CONTROL. Subjective appetite ratings were lower after breakfast and lunch in MCT+WPI (P=0.001).Conclusions Sequential consumption of MCT and WPI preloads did not affect diurnal or 24h glycaemia but lowered PPG and 24h glycaemic variability in individuals with T2D. These effects were associated with increased circulating β-hydroxybutyrate, PYY and GIP, and suppression of appetite.Clinical Trial Registry Number ClinicalTrials.gov Identifier NCT04905589 URL OF REGISTRATION: https://clinicaltrials.gov/study/NCT04905589.