GLycaemic Outcomes With Whey Protein in ageING (GLOWING)

Whey Protein Dose-response Effect on Daily Glycaemic Excursions in Very Old Individuals With Type 2 Diabetes

The goal of this placebo-controlled, partial crossover design study is to identify the impact of consuming whey protein before meals on free-living glucose control in older adults living with type 2 diabetes.

The primary specific objective is to determine the effect of a thrice daily whey protein pre-meal supplementation at two doses, on glucose excursions over a 7-day free-living period in adults aged 75-90 years of age, living with type 2 diabetes, compared with a non-protein placebo.

Participants will consume the whey protein and placebo for 7 days each, before each meal. All participants will consume the placebo and one of two doses of whey protein, in a randomised order.

Study Overview

• Status: Recruiting
• Conditions: Type 2 Diabetes
• Intervention / Treatment: Dietary supplement: Glycaemic control with whey protein; Dietary supplement: Glycaemic control with different doses of whey protein

Detailed Description

Within the study, the researchers will look at the effect of supplemental whey protein at moderate and low doses in comparison to each other and a protein-free placebo on glycaemic control in older adults aged between 75-90 years of age, living with type 2 diabetes.

Glycaemic control (glucose excursions) will be monitored under free-living conditions over a 7-day period using continuous glucose monitors (CGMs). Participants will be randomised to consume one of the two whey protein doses as well as the protein-free placebo on a separate 7-day period. The order of consuming whey protein or the protein-free placebo will be randomised and counterbalanced. This study is under the evidence that in younger people living with type 2 diabetes, a moderate dose of whey protein improves glucose time in range and lessens extreme postprandial glucose excursions.

Participants will be free to consume their typical diet over this period, where the researchers will provide a diet diary for participants to enter in all foods and drinks they consume over this time period, as well as document the ingestion of the supplement before each main meal.

During an acute feeding period on the first ingestion of each supplement (start of each 7-day phase), the researchers will evaluate rates of gastric emptying, glucose and insulin concentrations and hormonal appetite markers through blood draws, as well as perceived appetite responses through visual analogue scales. This will be in a research kitchen where participants will consume the supplement and a controlled mixed meal afterwards to monitor excursions in appetite response and glycemia. The researchers will also investigate the impact of pre-meal protein feeding on renal markers following each 7-day phase via urine collection.

• Study Type: Interventional
• Enrollment (Estimated): 32
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Leigh Breen, PhD; Phone Number: +44 (0)1214144109; Email: l.breen@bham.ac.uk
• Study Contact Backup: Name: Marie Korzepa, PhD; Email: m.korzepa@bham.ac.uk

Study Locations

• United Kingdom
  • Birmingham, United Kingdom
    • Recruiting
    • Heartlands Hospital
    • Contact: Srikanth Bellary, MD; Phone Number: 0121 4240234
  • West Midlands
    • Birmingham, West Midlands, United Kingdom, B15 2TT
      • Enrolling by invitation
      • School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Older Adult
• Accepts Healthy Volunteers: Yes

Description

• Male or female
• 75-90 years old
• Type 2 Diabetes (confirmed with glycated haemoglobin (HbA1c) >6.5% in clinic or in SportExR)
• Stable body mass (body mass index (BMI) ≤40kg/m2)
• Generally healthy, assessed via a General Health Questionnaire (GHQ)
• Some residual beta-cell activity (confirmed with urine test on induction)
• Normal or moderately increased albuminuria (needs to be below 300mg/g)
• Normal, mildly or moderately decreased glomerular filtration rate (GFR) (needs to be above 45ml/min/1.732).
• Able and willing to attend SportExR a total of 5 times: 1 induction and 2 testing visits and 2 return check-up visits.

Exclusion Criteria:

• <75 years old and over 90 years of age
• Currently on fast-acting insulin therapy (i.e., Humalog)
• Confirmed uncontrolled diabetes (HbA1C >10% or 85mmol/mol).
• Currently on GLP-1 therapy
• Habitual smoker or vaper
• Veganism
• Lactose or dairy intolerance
• Coeliac or gluten intolerance
• History of gastrointestinal disease
• Experienced a hyperglycaemic or hypoglycaemic event requiring treatment in the past 12 months
• Recent Ischemic stroke (<3 months).
• Use of anticoagulants (e.g. warfarin, rivaroxaban)
• Considered unwilling or unable to comply with the study protocol requirements by the research team

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Triple

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: pre-meal low dose whey protein; Low whey protein dose administration before meals	Dietary supplement: Glycaemic control with whey protein; Comparing pre-meal supplementation of whey protein to protein-free placebo.; Dietary supplement: Glycaemic control with different doses of whey protein; Comparing pre-meal supplementation of moderate whey protein to a low dose of whey protein.
Active Comparator: pre-meal moderate dose whey protein; Moderate whey protein dose administration before meals	Dietary supplement: Glycaemic control with whey protein; Comparing pre-meal supplementation of whey protein to protein-free placebo.; Dietary supplement: Glycaemic control with different doses of whey protein; Comparing pre-meal supplementation of moderate whey protein to a low dose of whey protein.
Placebo Comparator: pre-meal protein-free placebo; protein-free placebo administration before meals	Dietary supplement: Glycaemic control with whey protein; Comparing pre-meal supplementation of whey protein to protein-free placebo.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Measurement of changes in free-living glycaemic control	Time spent in normal glucose range, under free-living conditions with pre-meal supplementation (measured by continuous glucose monitors)	7 days, two occasions
Changes in postprandial glucose concentrations in blood	Amplitude of post-meal blood glucose following supplement(s) and controlled meal	4 hours, two occasions
Concentrations of insulin postprandially in blood	Insulin appearance in blood following supplement(s) and controlled meal	4 hours, two occasions

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Concentrations of amino acids postprandially in blood	Total amino acid appearance in blood following supplement(s) and controlled meal	4 hours, two occasions
Concentrations of postprandial appetite hormones	Postprandial appetite hormone concentrations in blood following supplement(s) and controlled meal	4 hours, two occasions
Rate of gastric emptying	Rate of gastric emptying using acetaminophen appearance in the blood following its consumption with supplement(s) and controlled meal.	4 hours, two occasions
Changes in renal function markers after each 7-day phase	Measurement of markers of renal function from urine following each 7-day phase	2 urine samples, 2 occasions
Assessment of nitrogen balance from urine after each 7-day phase	Nitrogen balance from 24-hour urine collection after each 7-day phase	24 hours, two occasions
Measurement of blood lipid concentration	Total cholesterol measurement in blood at rest	1 blood draw (obtained from the first blood draw as part of 4 hour visit)
Optional qualitative assessment of perceptions to supplementation	Optional interview for participants to share perceptions of pre-meal supplementation	60 minutes

Collaborators and Investigators

• Sponsor: University of Birmingham
• Collaborators: Newcastle University
• Investigators: Principal Investigator: Leigh Breen, PhD, University of Birmingham and University of Leciester

Study record dates

Study Major Dates

• Study Start (Estimated): December 1, 2025
• Primary Completion (Estimated): August 1, 2026
• Study Completion (Estimated): December 1, 2026

Study Registration Dates

• First Submitted: November 18, 2025
• First Submitted That Met QC Criteria: December 2, 2025
• First Posted (Actual): December 16, 2025

Study Record Updates

• Last Update Posted (Actual): December 16, 2025
• Last Update Submitted That Met QC Criteria: December 2, 2025
• Last Verified: December 1, 2024

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Endocrine System Diseases; Metabolic Diseases; Glucose Metabolism Disorders; Diabetes Mellitus; Nutritional and Metabolic Diseases; Diabetes Mellitus, Type 2; Amino Acids, Peptides, and Proteins; Proteins; Food; Diet, Food, and Nutrition; Physiological Phenomena; Food and Beverages; Dairy Products; Milk; Dietary Proteins; Milk Proteins; Animal Proteins, Dietary; Whey; Whey Proteins
• Other Study ID Numbers: RG_24-052

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No