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

Official title

Net-IOB & Exercise Toolkit Pilot Trial: Randomized, Crossover Evaluation of a Behavioral Decision Support Advisor to Improve Glycemic Safety During and After Exercise in Adults With Type 1 Diabetes (NEXT)

Overview

This study evaluates a clinician-facing decision-support toolkit designed to assist adults with type 1 diabetes in preparing for moderate-intensity exercise. The netIOB \& Exercise Toolkit (NEXT) integrates recent glucose data and insulin delivery history to provide individualized suggestions regarding exercise timing, insulin adjustments, and carbohydrate intake. Adults with type 1 diabetes will complete three supervised exercise sessions under different pre-exercise guidance approaches: (A) published consensus-based standard-of-care guidance, (B) usual personal care routines, and (C) guidance informed by the NEXT Toolkit. A healthy adult control group will complete a single supervised exercise session to provide comparative physiologic data.

Detailed description

People with type 1 diabetes frequently experience variable glucose responses before, during, and after physical activity, including exercise-associated hypoglycemia and the need for unplanned carbohydrate intake. Although consensus-based recommendations exist to guide exercise preparation, many individuals continue to rely on trial-and-error strategies that can be burdensome or difficult to generalize across activities.

This study evaluates the netIOB \& Exercise Toolkit (NEXT), a software-based, clinician-facing decision-support system intended to contextualize exercise preparation using recent continuous glucose monitoring (CGM) data and insulin delivery history. The Toolkit estimates net insulin-on-board relative to an individual's programmed basal insulin profile and presents structured, non-automated suggestions related to exercise timing, insulin target adjustments, and carbohydrate intake. All decisions remain under clinician and participant control.

The primary study population consists of adults with type 1 diabetes who complete three supervised, moderate-intensity exercise sessions in a randomized, three-period crossover design. Each session is conducted under a different pre-exercise strategy: consensus standard-of-care guidance, usual personal care routines, or guidance informed by the NEXT Toolkit. Sessions are separated by washout periods to minimize physiologic carryover, and glycemic, insulin delivery, and behavioral outcomes are assessed during exercise and for up to 48 hours post-exercise.

In addition, a healthy adult control group completes a single supervised exercise session without pre-exercise glucose or insulin management interventions. This group is included to provide comparative physiologic context for exploratory analyses.

Exploratory analyses will examine relationships between pre-exercise net insulin-on-board (netIOB) strata and glycemic, insulin, and treatment outcomes across exercise sessions. These analyses are intended to characterize patterns of response rather than to test formal efficacy hypotheses.

Participants in both the type 1 diabetes and healthy control groups will wear a commercially available continuous ketone monitoring (CKM) sensor (SiBio KS1) for exploratory data collection during exercise and defined post-exercise monitoring periods. CKM data are collected solely for research purposes, are not used to guide clinical or study-related decisions, and are not intended to evaluate device performance.

The NEXT Toolkit is classified as a non-significant risk, IDE-exempt investigational tool. Results from this pilot study are intended to inform future research design and the development of transparent, open-access methods for studying exercise physiology and glucose management in diabetes.

Interventions

• Behavioral Standard-of-Care Guidance (SoC)
  Study staff provide insulin and carbohydrate adjustment advice based on consensus exercise management guidelines (Moer et al., 2024), tailored to the planned activity.
• Behavioral Usual Care (UC)
  Participants independently manage their insulin and carbohydrate decisions around exercise, using their routine practices without study-provided guidance.
• Device netIOB & Exercise Toolkit (NEXT)
  An investigational software tool generates individualized insulin and carbohydrate adjustment recommendations before and after exercise using CGM data and recent insulin delivery. Study physicians review and relay these recommendations to participants.
• Device Continuous Glucose Monitoring
  Continuous glucose monitoring using an FDA-cleared system (Dexcom G7) for research data collection during and after exercise. CGM data are used to assess glycemic responses and are not used to evaluate device performance or accuracy.
• Device Continuous Ketone Monitoring
  A commercially available continuous ketone monitoring (CKM) device will be used for exploratory data collection during and after exercise. Ketone data are collected for research purposes only and are not used for clinical decision-making or to evaluate device performance.

Primary outcome measures

• Composite Score of Glycemic Safety and Carbohydrate Burden [Time frame: 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).]

Secondary outcome measures (11)

• Percent-Based Continuous Glucose Monitor Metrics [Time frame: 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).]
• Glucose Concentration and Variability Metrics from Continuous Glucose Monitor [Time frame: 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).]
• Frequency of Hypoglycemic Events [Time frame: Exercise (0 to 90 minutes), Early Post-Exercise (0 to 6 hours after exercise); total of 7.5 hours per visit (3 visits).]
• Glucose Nadir Value [Time frame: Exercise (0 to 90 minutes), Early Post-Exercise (0 to 6 hours after exercise); total of 7.5 hours per visit (3 visits).]
• Time to First Hypoglycemic Event [Time frame: Exercise (0 to 90 minutes), Early Post-Exercise (0 to 6 hours after exercise); total of 7.5 hours per visit (3 visits).]
• Carbohydrate Consumption for Hypoglycemia Prevention/Treatment [Time frame: Exercise (0 to 90 minutes); total of 1.5 hours per visit (3 visits).]
• Total and Programmed Insulin Delivery [Time frame: 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).]
• Frequency of User-Initiated Pump Adjustments [Time frame: 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).]
• Duration of User-Initiated Pump Adjustments [Time frame: 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).]
• Baseline and Peak Ketone Levels [Time frame: Baseline (immediately prior to exercise) and Exercise (0 to 90 minutes from exercise).]
• Ketone Exposure (AUC) During and After Exercise [Time frame: Exercise (0 to 90 minutes), Early Post-Exercise (0 to 6 hours after exercise) per visit.]

Eligibility criteria

Inclusion Criteria Inclusion Criteria: All Participants (Type 1 Diabetes and Healthy Control Groups)

• Adults between the age of 18-60 years
• Able to perform moderate intensity walking for 60 minutes (target 40-60% age-predicted maximal heart rate).
• Willing and able to comply with study procedures, including supervised exercise visits and device wear
• Able to provide written informed consent

Inclusion Criteria: Type 1 Diabetes Group Only

• Clinical diagnosis of type 1 diabetes for >1 year, based on the investigator's clinical judgement
• Current use of continuous subcutaneous insulin infusion with Tandem Control-IQ and a compatible continuous glucose monitor (CGM) for >1 month prior to enrollment
• Stable insulin delivery regimen, with no planned changes to insulin pump settings or insulin dosing strategy during the study period
• Consistent CGM use during the month prior to enrollment (>80% data availability)

Inclusion Criteria: Health Control Group Only

• No diagnosis of diabetes or other disorders of glucose metabolism
• Not using insulin or glucose-lowering medications

Exclusion Criteria Exclusion Criteria: All Participants

• Intercurrent illness or medical condition that precludes safe participation in moderate-intensity exercise (e.g., unstable cardiopulmonary disease, uncontrolled arrhythmia, or uncontrolled hypertension), as previously assessed by the participant's primary care physician
• Known coronary artery disease with symptoms limiting moderate physical activity, or history of myocardial infarction, percutaneous coronary intervention, or coronary artery bypass grafting within the past 12 months
• Pregnancy, lactation, or plans to become pregnant during the study period
• Renal insufficiency with estimated GFR <45 mL/min/1.73 m², dialysis dependence, or adrenal insufficiency
• Concurrent participation in another interventional drug or device study within 30 days prior to enrollment
• Inability to comply with study procedures or safety requirements (e.g., inability to achieve target heart-rate zone, attend scheduled visits, or enable required device data access), or otherwise deemed unsuitable by the investigator

Exclusion Criteria: Type 1 Diabetes Group Only

• Use of non-CSII insulin delivery, including long-acting injectable or inhaled insulin, during the study period
• Use of medications with potential to substantially affect glycemia (e.g., SGLT-2 inhibitors, GLP-1 receptor agonists, or GIP agonists), unless on a stable regimen with no planned changes during the study
• Use of systemic corticosteroids within 4 weeks prior to participation
• History of severe hypoglycemia (requiring third-party assistance) or diabetic ketoacidosis within the prior 6 months

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: Yes

Study design

Allocation

Randomized

Model

Crossover

Masking

Open label

Primary purpose

Supportive care

Study locations

United States · 1 center

• Stanford University — Palo Alto

Identifiers

NCT: NCT07226583 · 82224 · 2407-07175

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗