Comparing how exercise affects blood sugar in adults with and without Type 1 diabetes.

Inter- and Intraindividual Variability of the Acute Glucose Response to Exercise in Healthy Adults and People Living With Type 1 Diabetes: A Cross-over Replicate Trial

We will see if a standardized bout of cycling causes similar blood sugar changes within the same person and between people, in adults with Type 1 diabetes and in healthy adults, using continuous glucose monitors and finger‑stick checks.

Quick facts

• Phase: NA
• Study type: Interventional
• Enrollment: 24 (estimated)
• Ages: 18 Years to 60 Years
• Sex: All
• Sponsor: University College Dublin (other)
• Locations: 1 site (Dublin, Dublin)
• Trial ID: NCT07209930 on ClinicalTrials.gov

What this trial studies

This is a randomized replicate crossover trial with two parallel phases: one for adults with Type 1 diabetes and one for healthy adults, each recruiting about 12 participants. After baseline testing (including body composition and VO2max), participants complete two test conditions (exercise on a cycle ergometer and rest) in randomized order and then repeat the same order the following week to measure reproducibility. Glucose is tracked continuously by CGM and intermittently by capillary blood sampling after a standardized breakfast, with at least 72 hours between test visits. The design compares within‑person repeatability and between‑person variability and also evaluates agreement between CGM and finger‑stick glucose values.

Who should consider this trial

Good fit: Adults aged 18–60 who either have Type 1 diabetes for more than 18 months with intact hypoglycaemia self‑awareness and ability to self‑manage their diabetes, or are healthy adults without diabetes who engage in physical activity at least once weekly, are suitable candidates.

Not a fit: People with cardiovascular disease or other contraindications to exercise, pregnancy, chronic renal or liver disease, diagnosed eating disorders, active infection, or those unable to safely self‑manage diabetes (including loss of hypoglycaemia awareness) are unlikely to benefit or be eligible.

Why it matters

Potential benefit: If successful, the results could help predict individual glucose responses to exercise and improve personalized guidance for safe physical activity in people with Type 1 diabetes.

How similar studies have performed: Prior research has documented substantial variability in glucose responses to exercise and mixed agreement between CGM and capillary blood, so this work builds on existing but unresolved evidence.

Eligibility criteria

Inclusion Criteria:

(Healthy and T1D phases):

* age between 18 and 60 years old;
* being healthy individuals;
* engagement in physical activity at least once a week; (T1D phase):
* diagnosis of T1D for \>18 months;
* hypoglycaemia self awareness.

Exclusion Criteria:

(Healthy and T1D phases)

* presence of cardiovascular disease or contraindications to exercise;
* infectious or inflammatory conditions;
* chronic renal or liver disease;
* pregnancy;
* gestational diabetes;
* diagnosed eating disorders;
* any physical or mental condition preventing participation; (Healthy phase)
* diabetes mellitus (type 1 or type 2); (T1D phase)
* inability to self-manage diabetes.

Where this trial is running

Dublin, Dublin

• University College Dublin — Dublin, Dublin, Ireland (RECRUITING)

Study contacts

• Study coordinator: Veronica Merlo

Conditions: Exercise, Healthy Participants, Glucose Variability, Type 1 Diabetes, reproducibility, exercise, Type 1 diabetes, glucose