The influence of whey protein on free-living glycaemic control in type 2 diabetes

INTERVENTION: Participants will randomly consume either a small dose (15g) of whey protein (Arla Foods Ingredients Group P/S., [AFI], Denmark) or a protein‐depleted placebo supplement (AFI, Denmark) 10 minutes before each of their main meals (breakfast, lunch, dinner) for a period of 7 days. Prior to and immediately following each 7 day period, participants will perform a "mixed meal tolerance test" where they will consume their assigned supplement 10 minutes before a breakfast and lunch meal. Trial order will be determined by an online randomiser (www.randomization.com), randomly assigning participants, in a balanced permutation, into two treatment groups. Twenty‐two adults with type 2 diabetes mellitus treated with diet and lifestyle modifications and/or oral medications will be recruited into a nutritional intervention examining the influence of a novel small whey protein beverage on free‐living blood glucose control and energy intake. Patients will attend the NIHR Clinical Research Facility (CRF), Royal Victoria Infirmary, Newcastle upon Tyne a total of 6 times over a 5‐week period. On patients first and fourth visit, a continuous glucose monitoring system (G6, Dexcom, USA) will be fitted to capture pre‐trial and free‐living glucose control. On subsequent visits [visits 2, 3, 5 and 6] patients will enter the CRF to perform a mixed meal tolerance test. A standardised evening meal ( 900 kcal) will be provided to be consumed before each mixed meal tolerance test to ensure standardisation between appetite and gut hormone parameters. Following an overnight fast, patients will enter the CRF to perform a mixed meal tolerance test to assess acute and intermediate effects of whey protein pre‐meal consumption on plasma glucose, insulin, lipid and gut peptide responses [visits 2, 3, 5 and 6]. In a single‐blinded, randomised, counterbalanced manner, patients will consume a protein‐rich whey [WP; 15g protein] or a protein‐depleted shot [P CONDITION: Type 2 diabetes mellitus ; Nutritional, Metabolic, Endocrine ; Type 2 diabetes mellitus PRIMARY OUTCOME: Postprandial glycaemic responses (incremental area under the curve) to patient’s free‐living main meals (breakfast, lunch and dinner) following prior consumption of the protein‐rich and protein‐depleted supplement (i.e. “pre‐loadâ€?). Glycaemic responses will be measured from interstitial glucose concentrations collected from patient's continuous glucose monitoring system (CGM) over a 7‐day free‐living period, where a postprandial period will be defined as an uninterrupted 2‐hour phase following commencement of a reported meal. Postprandial glycaemic responses will be calculated using the trapezoidal rule. INCLUSION CRITERIA: 1. Diagnosed with type 2 diabetes mellitus for at least 1 year prior to participation in this trial. 2. Treated with either lifestyle modifications and/or oral medications, which have been stable for 3 months or more. 3. Weight stable for 1 month or more (i.e. weight has not fluctuated by more than 1kg prior to study enrolment). 4. HbA1c of below 9.5% (80mmol/mol) 5. Aged between 30‐68 years of age 6. Regularly consume breakfast 7. Adhere to a normal sleep/wake cycle SECONDARY OUTCOME: ; 1. Energy intake (kcal) measured by an ad libitum lunch meal served during the mixed meal tolerance tests [visits 2, 3, 5 and 6]. Energy intake will be calculated from weighing both served and unserved amounts of the test meal, and before and after meal consumption.; 2. Time‐course changes in subjective appetite sensations measured using a linear visual analogue scale during the mixed meal tolerance tests [visits 2, 3, 5 and 6].; 3. Time‐course responses in blood glucose, insulin, lipids and gut hormones following a standardised mixed‐nutrient breakfast meal prior to and immediately following the 7 day period. All markers will be analysed by routinely available assays [mixed meal tolerance tests: visits 2, 3, 5 and 6].; 4. Changes in pro‐inflammatory cytokine concentrations (interleukin‐6, tumour necrosis factor alpha and high‐sensitivity C‐reactive protein) following 7‐days of supplementation. Pro‐inflammatory cytokine concentrations will be measured from a fasting blood sample collected during the mixed‐meal tolerance tests measured by routinely available assays [mixed meal tolerance tests: visits 2, 3, 5 and 6].; 5. Patient experiences and attitudes towards consuming a nutrient pre‐load as a mode to treating their diabetes as analysed by a patient interview conducted at the end of the trial [visit 6]. Interviews will be transcribed into a written format and analysed for themes.; 6. Markers of free‐living glycaemic variability (MAGE, M‐Value, SD and CONGA) will be calculated from interstitial glucose concentrations measured from a CGM over a 7‐day free‐living period using EasyGV V9.0.R2 (Oxford University, UK). Circulating concentrations of 1, 5‐anhydroglucitol collected from fasting blood samples during the mixed‐meal tolerance tests will be measured by routinely available assays [visits 2, 3, 5 and 6].; 7. Time spent in hypoglycaemia (< 3.9 mmol/L), euglycaemia (3.9 ‐ 10 mmol/L), hyperglycaemia (10 – 13.9 mmol/L) and severe hyperglycaemia (> 13.9 mmol/L) during a 7‐day free‐living period as measured from interstitial glucose concentrations reported from the CGM. Time spent in subsequent thresholds will be expressed as a % of time: number of readings within a specific threshold divided by total CGM readings provided.; 8. Free‐living energy intake (kcal) will be measured using an online dietary recall (Intake 24, UK), completed daily throughout the 7‐day free‐living period.;