Using a Personalized Decision Support Tool to Help People With Type 1 Diabetes Manage Exercise

Not Applicable

Not yet recruiting

• Conditions: Type 1 Diabetes Mellitis; Type 1 Diabetes (T1D); Type 1 Diabetes Mellitus (T1DM)

• Registration Number: NCT07226583
• Lead Sponsor: Stanford University

Brief Summary

This study evaluates a digital decision-support tool designed to help individuals with type 1 diabetes prepare for exercise. This netIOB \& Exercise Tool (NEXT) uses glucose data and insulin delivery history to recommend individualized strategies such as carbohydrate intake, insulin adjustments, or delays in exercise start time.

Participants will complete three structured aerobic or mixed-exercise sessions using different guidance approaches:

(A) published consensus-based standard-of-care guidelines (B) usual personal care routines (C) the NEXT tool

The study compares glucose outcomes, safety, and carbohydrate use across these conditions to inform better exercise preparation and support tools for people with diabetes.

Detailed Description

People with type 1 diabetes often experience unpredictable changes in blood glucose levels before, during, and after physical activity. While consensus guidelines exist to help mitigate these risks, many individuals continue to encounter hypoglycemia or rely on excessive carbohydrate intake around exercise.

This study evaluates a software-based tool, netIOB \& Exercise Toolkit (NEXT), that provides real-time, individualized guidance for exercise preparation. The tool uses data from continuous glucose monitors (CGMs), insulin delivery history, and exercise timing to suggest adjustments such as carbohydrate intake, temporary targets, or delayed start times. Its goal is to reduce hypoglycemia and carbohydrate burden while preserving exercise safety and feasibility.

The trial uses a randomized, crossover design in which participants complete three supervised moderate-intensity exercise sessions, each under a different preparation strategy. The guidance methods include consensus standard-of-care, usual personal care, and the investigational NEXT tool. Each session is followed for 48 hours to assess glycemic and behavioral outcomes.

Exploratory analyses will stratify glycemic and treatment outcomes based on pre-exercise net insulin-on-board (netIOB) levels, categorized into predefined strata (e.g., 0.0-1.0u, 1.0-2.0u, 2.0-3.0u, 3.0u+), to assess potential effect modification across intervention arms.

The NEXT tool is investigational and classified as IDE-exempt. Findings from this study may inform the design of future clinical trials and support the development of open-source methods for exercise preparation in diabetes.

Study Timeline

• Status Verified: 2025-10
• Study First Submitted: 2025-10-07
• Study First Submitted QC: 2025-11-06
• Study First Posted: 2025-11-10
• Last Update Submitted: 2025-11-11
• Last Update Posted: 2025-11-13
• Study Start: 2025-12-01
• Primary Completion: 2026-06
• Study Completion: 2026-06-01

Recruitment & Eligibility

• Status: NOT_YET_RECRUITING
• Sex: All
• Target Recruitment: 10

Inclusion Criteria

• Adults between the age of 18-60 years
• Diagnosis of type 1 diabetes for >1 year (based on investigator's clinical judgement)
• Using Tandem Control-IQ and Dexcom G7 for ≥1 month
• Able to sustain moderate intensity walking for 60 minutes (target 50-60% age-predicted HR max) without limitation.
• Use of a stable insulin delivery regimen, with no planned changes in settings or dosing strategy during the study period, and consistent continuous glucose monitor (CGM) use in the prior 1 month (>80% data)

Exclusion Criteria

• Use of non-continuous subcutaneous insulin infusion (CSII) during study, including long-acting or inhalable insulins.
• Use of other medications with the potential to confound glycemia (including SGLT-2 inhibitors, GIP or GLP-1 receptor agonists) unless on a stable regimen with no planned changes during the study.
• Use of systemic steroids within 4 weeks of planned study participation.
• Severe hypoglycemia (requiring assistance) or DKA within the prior 6 months.
• Intercurrent illness or medical conditions that preclude safe participation in moderate-intensity exercise (e.g. unstable cardiopulmonary disease, uncontrolled arrhythmia, or uncontrolled hypertension), as previously assessed by the individual's primary care physician.
• Pregnancy, lactation, or planned pregnancy during participation.
• Renal insufficiency with eGR <45 mL/min/1.73 m2, dialysis, or adrenal insufficiency.
• Known coronary disease or angina that limits moderate activity, or myocardial infarction/PCI/CABG within 12 months.
• Concurrent participation in another interventional drug/device study within 30 days
• Inability to comply with study procedures or safety requirements (e.g., cannot achieve target HR zone, cannot attend visits, or cannot enable device data access), or otherwise deemed unsuitable by the investigator.

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: CROSSOVER

Primary Outcome Measures

Name	Time	Method
Composite Score of Glycemic Safety and Carbohydrate Burden	Baseline (1 hour pre-exercise), Exercise (0 to 90 minutes), Early Post-Exercise (0 to 6 hours after exercise), Mid Post-Exercise (6 to 24 hours after exercise), Late Post-Exercise (24 to 48 hours after exercise); total of 50.5 hours per visit (3 visits).	This composite outcome integrates glycemic safety and carbohydrate burden during and after exercise.; The Glycemic Safety subscore is calculated from percent time spent \<70 mg/dl and \<54 mg/dl, number of treated hypoglycemic events, and nadir glucose, with heavier penalties for Level 2 hypoglycemia.; The Carbohydrate Burden Subscore is based on total grams og carbohydrates consumed and the number of treatment episodes.; A glycemic safety and carbohydrate burden composite metric score of zero is equal to no risk of hypoglycemia without carbohydrate consumption.

Secondary Outcome Measures

Name	Time	Method
Percent-Based Continuous Glucose Monitor Metrics	Baseline (1 hour pre-exercise), Exercise (0 to 90 minutes), Early Post-Exercise (0 to 6 hours after exercise), Mid Post-Exercise (6 to 24 hours after exercise), Late Post-Exercise (24 to 48 hours after exercise); total of 50.5 hours per visit (3 visits).	Assess standard continuous glucose monitoring (CGM) metrics during defined time windows relative to exercise (0-90 minutes, 0-6 hours, 6-24 hours, and 24-48 hours post-exercise).; These include: * Percent Time in Range (TIR): 70-180 mg/dL; * Percent Time Below Range (TBR): \<70 mg/dL and \<54 mg/dL; * Percent Time Above Range (TAR): \>180 mg/dL and \>250 mg/dL
Glucose Concentration and Variability Metrics from Continuous Glucose Monitor	Baseline (1 hour pre-exercise), Exercise (0 to 90 minutes), Early Post-Exercise (0 to 6 hours after exercise), Mid Post-Exercise (6 to 24 hours after exercise), Late Post-Exercise (24 to 48 hours after exercise); total of 50.5 hours per visit (3 visits).	Mean glucose level, glucose standard deviation (SD), and coefficient of variation (CV) will be calculated using CGM data collected over defined time periods relative to exercise. These metrics describe overall glycemic variability and will be used to assess the stability of glucose control following each intervention.; Units of Measure: Mean glucose: mg/dL SD: mg/dL CV: %
Frequency of Hypoglycemic Events	Exercise (0 to 90 minutes), Early Post-Exercise (0 to 6 hours after exercise); total of 7.5 hours per visit (3 visits).	Number of hypoglycemic episodes per participant at thresholds of \<70 mg/dL and \<54 mg/dL, stratified by treatment arm. Events will be classified as treated or untreated.
Glucose Nadir Value	Exercise (0 to 90 minutes), Early Post-Exercise (0 to 6 hours after exercise); total of 7.5 hours per visit (3 visits).	Lowest glucose value (nadir mg/dl) recorded per participant during exercise period and 0-6 hours post-exercise, as measured by CGM.
Time to First Hypoglycemic Event	Exercise (0 to 90 minutes), Early Post-Exercise (0 to 6 hours after exercise); total of 7.5 hours per visit (3 visits).	Time (in minutes) from exercise start to the first hypoglycemic episode (\<70 mg/dL) for each participant.
Carbohydrate Consumption for Hypoglycemia Prevention/Treatment	Exercise (0 to 90 minutes); total of 1.5 hours per visit (3 visits).	Quantify carbohydrate use related to exercise using: * Total grams of carbohydrate consumed; * Number of carbohydrate treatment episodes; * Categorization as prophylactic or reactive
Total and Programmed Insulin Delivery	Baseline (1 hour pre-exercise), Exercise (0 to 90 minutes), Early Post-Exercise (0 to 6 hours after exercise), Mid Post-Exercise (6 to 24 hours after exercise), Late Post-Exercise (24 to 48 hours after exercise); total of 50.5 hours per visit (3 visits).	Compare the total insulin delivered (actual) to the amount that would have been delivered based on the participant's pre-programmed basal rates. This includes both basal and bolus insulin.
Frequency of User-Initiated Pump Adjustments	Baseline (1 hour pre-exercise), Exercise (0 to 90 minutes), Early Post-Exercise (0 to 6 hours after exercise), Mid Post-Exercise (6 to 24 hours after exercise), Late Post-Exercise (24 to 48 hours after exercise); total of 50.5 hours per visit (3 visits).	Number of times participants manually modified insulin delivery during the exercise period, including suspensions, temporary targets, exercise mode, or basal rate changes.
Duration of User-Initiated Pump Adjustments	Baseline (1 hour pre-exercise), Exercise (0 to 90 minutes), Early Post-Exercise (0 to 6 hours after exercise), Mid Post-Exercise (6 to 24 hours after exercise), Late Post-Exercise (24 to 48 hours after exercise); total of 50.5 hours per visit (3 visits).	Cumulative duration of user-initiated pump modifications, including time spent in temporary targets, pump suspensions, and exercise modes.

Trial Locations

Locations (1)

Stanford University; 🇺🇸 Palo Alto, California, United States