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

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.