Effects of Pre-Exercise Basal Insulin Manipulation on Glucose Dynamics in Females vs. Males With Type 1 Diabetes

NCT07550608 | Completed

• 1 other identifier: SZMC - 0272-23
• Study Type: interventional
• Target: 18
• Locations: 1 country
• Sites: 1

Brief Summary

The Purpose of the Study The purpose of this study is to compare how blood sugar levels change during exercise in men and women with type 1 diabetes (T1D). Researchers want to understand if biological sex affects the risk of low blood sugar (hypoglycemia) during physical activity. Additionally, the study examines whether reducing the background (basal) insulin dose before exercise is effective at keeping blood sugar stable. Study Population The study includes active adults (men and women) aged 18-45 who have lived with type 1 diabetes for at least 18 months and use an insulin pump. What Happens During the Study Participants complete three laboratory visits: Visit 1: A fitness test on a treadmill to measure the participant's aerobic capacity. Visits 2 \& 3: Two 60-minute moderate-intensity exercise sessions on a treadmill. In one session, participants reduce their basal insulin by 50% starting 90-120 minutes before exercising. In the other session, they maintain their usual insulin dose. Researchers measure blood sugar every 10 minutes during exercise and collect blood samples before and after the sessions to monitor hormone levels. Study Design This is a randomized crossover study, meaning every participant performs both exercise strategies in a random order to serve as their own control.

Conditions

Type 1 Diabetes

Keywords

type 1 diabetes; basal insulin rate reduction; physical activity; aerobic activity

Outcome Measures

Primary Outcomes (1)

• Mean Rate of Capillary Blood Glucose (CBG) Decline

  The average rate at which blood glucose levels decrease during the 60-minute moderate-intensity exercise session, measured in mg/dL per 10 minutes. This metric is used to characterize glucose dynamics and compare the impact of insulin reduction versus full dose across biological sexes.

  During the 60-minute exercise session.

Secondary Outcomes (4)

• Incidence of Exercise-Induced Hypoglycemia

  During the 60-minute exercise session.

• Time to Onset of Hypoglycemia

  During the 60-minute exercise session.

• Changes in Plasma Counter-Regulatory Hormone Levels

  Baseline (pre-exercise) and 60 minutes (immediately post-exercise).

• Substrate Utilization (Respiratory Exchange Ratio)

  Throughout the 60-minute exercise session.

Study Arms (2)

50% Basal Insulin Reduction (INS_RED)

OTHER

Participants perform a 60-minute moderate-intensity treadmill session after reducing their habitual basal insulin infusion rate by 50%. This reduction is initiated 90-120 minutes before the start of exercise.

Other: 50% Pre-Exercise Basal Insulin Rate Reduction (BIRR); Other: Habitual Basal Insulin Rate Maintenance

Full Habitual Basal Insulin (INS_FULL)

OTHER

Participants perform a 60-minute moderate-intensity treadmill session while maintaining their full habitual basal insulin infusion rate (no adjustment made prior to or during exercise).

Other: 50% Pre-Exercise Basal Insulin Rate Reduction (BIRR); Other: Habitual Basal Insulin Rate Maintenance

Interventions

50% Pre-Exercise Basal Insulin Rate Reduction (BIRR) OTHER

Participants are instructed to reduce their habitual basal insulin infusion rate by 50% using their continuous subcutaneous insulin infusion (CSII) pump. This reduction is initiated 90 to 120 minutes prior to the start of the 60-minute moderate-intensity treadmill exercise bout. The intervention is designed to evaluate if this proactive reduction mitigates the risk of exercise-induced hypoglycemia in both male and female recreational athletes with type 1 diabetes.

50% Basal Insulin Reduction (INS_RED); Full Habitual Basal Insulin (INS_FULL)

Habitual Basal Insulin Rate Maintenance OTHER

Participants perform a 60-minute moderate-intensity treadmill exercise bout while maintaining their full habitual basal insulin infusion rate as programmed in their CSII pump. No adjustments, reductions, or suspensions of the basal rate are made prior to or during the exercise session. This condition serves as the active comparator to evaluate standard glucose dynamics without anticipatory insulin manipulation.

50% Basal Insulin Reduction (INS_RED); Full Habitual Basal Insulin (INS_FULL)

Eligibility Criteria

• Age: 18 Years - 45 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64)

You may qualify if:

• Adults aged 18 to 45 years.
• Diagnosis of Type 1 Diabetes (T1D) for at least 18 months.
• Current use of an insulin pump (Continuous Subcutaneous Insulin Infusion - CSII) for diabetes management.
• Regular physical activity level, defined as at least 150 minutes of aerobic exercise per week across three or more sessions for at least 4 weeks prior to the study.
• Ability to perform 60 minutes of continuous treadmill running.
• Aerobic fitness level (VO2peak) of ≥ 30 mL·kg-¹·min-¹ for females or ≥ 32 mL·kg-¹·min-¹ for males.

You may not qualify if:

• Most recent HbA1c \> 9.9% (85 mmol/mol).
• C-peptide levels ≥ 0.7 nmol/L.
• Presence of significant diabetes complications (e.g., proliferative retinopathy, nephropathy, or symptomatic neuropathy).
• Use of concomitant medications affecting glucose metabolism other than insulin (e.g., steroids, SGLT2 inhibitors, GLP-1 receptor agonists, or non-selective beta-blockers).
• History of hypoglycemia unawareness.
• Occurrence of severe hypoglycemia resulting in seizure, coma, or hospitalization within the 6 months prior to recruitment.
• Adherence to a low-carbohydrate or ketogenic diet (\<30 g of carbohydrates per day).
• Current engagement in shift work.
• For female participants: presence of primary or secondary amenorrhea (cessation of menstruation for \>12 months).
• Uncontrolled hypertension (Systolic BP \> 200 mmHg or Diastolic BP \> 110 mmHg).
• Known cardiovascular disease or significant cardiovascular risk factors (e.g., ischemic heart disease).

Sponsors & Collaborators

• Naama Constantini: lead

Study Sites (1)

Sylvan Adams Sport Institute, Tel Aviv University

Tel Aviv, Israel

Location

Related Publications (2)

• Moser O, Riddell MC, Eckstein ML, Adolfsson P, Rabasa-Lhoret R, van den Boom L, Gillard P, Norgaard K, Oliver NS, Zaharieva DP, Battelino T, de Beaufort C, Bergenstal RM, Buckingham B, Cengiz E, Deeb A, Heise T, Heller S, Kowalski AJ, Leelarathna L, Mathieu C, Stettler C, Tauschmann M, Thabit H, Wilmot EG, Sourij H, Smart CE, Jacobs PG, Bracken RM, Mader JK. Glucose management for exercise using continuous glucose monitoring (CGM) and intermittently scanned CGM (isCGM) systems in type 1 diabetes: position statement of the European Association for the Study of Diabetes (EASD) and of the International Society for Pediatric and Adolescent Diabetes (ISPAD) endorsed by JDRF and supported by the American Diabetes Association (ADA). Pediatr Diabetes. 2020 Dec;21(8):1375-1393. doi: 10.1111/pedi.13105. Epub 2020 Oct 13.

  PMID: 33047481 BACKGROUND

• Riddell MC, Gallen IW, Smart CE, Taplin CE, Adolfsson P, Lumb AN, Kowalski A, Rabasa-Lhoret R, McCrimmon RJ, Hume C, Annan F, Fournier PA, Graham C, Bode B, Galassetti P, Jones TW, Millan IS, Heise T, Peters AL, Petz A, Laffel LM. Exercise management in type 1 diabetes: a consensus statement. Lancet Diabetes Endocrinol. 2017 May;5(5):377-390. doi: 10.1016/S2213-8587(17)30014-1. Epub 2017 Jan 24.

  PMID: 28126459 BACKGROUND

MeSH Terms

Conditions

Diabetes Mellitus, Type 1; Motor Activity

Condition Hierarchy (Ancestors)

Diabetes Mellitus; Glucose Metabolism Disorders; Metabolic Diseases; Nutritional and Metabolic Diseases; Endocrine System Diseases; Autoimmune Diseases; Immune System Diseases; Behavior

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: BASIC SCIENCE
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: SPONSOR INVESTIGATOR
• PI Title: Prof.

Model Details: This randomized, two-period, two-sequence crossover study stratifies participants by biological sex. Participants are randomly assigned to one of two sequences: Sequence A: 60-minute moderate-intensity exercise with a 50% basal insulin reduction (INS\_RED) 90-120 mins pre-exercise, followed by a minimum 48-hour washout, then the same exercise session with the full habitual basal dose (INS\_FULL). Sequence B: 60-minute exercise with the full habitual dose (INS\_FULL), followed by a minimum 48-hour washout, then exercise with a 50% basal reduction (INS\_RED). Randomization: Block randomization within each sex strata ensures an equal distribution of starting conditions. To minimize hormonal influence on glucose metabolism, sessions for female participants are scheduled during the early follicular phase of the menstrual cycle.

Study Record Dates

• First Submitted: April 19, 2026
• First Posted: April 24, 2026
• Study Start: October 20, 2023
• Primary Completion: July 1, 2025
• Study Completion: July 1, 2025
• Last Updated: April 30, 2026

Record last verified: 2026-04

Data Sharing

• IPD Sharing: Will not share

Locations

IL (1)