Fasted Exercise Training in Type 1 Diabetes (FED-T1D)

People with type 1 diabetes (PwT1D) are encouraged to increase their physical activity (PA). Increasing the amount of PA can be difficult, especially for PwT1D who experience barriers to exercise. Therefore, simply recommending that PwT1D preform more exercise may not be the most effective prescription in the long term. Recent short-term studies have s suggest that exercise performed before eating (fasted) causes blood sugars to decrease less or even increase, compared exercise performed after a meal, which usually causes blood sugar to decrease. To date, no long-term study has compared the effects of exercise performed with or without eating beforehand in people with T1D.

This study will compare the effects of 12 weeks of exercise before breakfast compared to 12 weeks of exercise after breakfast. It is expected that exercise before breakfast (i.e., in the fasted state) will lead to larger reductions in overall insulin dose, without the addition of more exercise.

Inclusion criteria

• Clinical diagnosis of type 1 diabetes for 5 or more years.
• Treatment using an insulin pump with no change in treatment modality for > 2 continuous months and willing to share CGM data with the research team. Insulin delivery can be managed using either manual open-loop system (non-AID) or a hybrid closed loop (AID) systems.
• Using rapid (e.g., Aspart, Lispro or Glulisine) or ultra-rapid (e.g., FiAsp) acting insulin analogs.
• HbA1c 7.0-9.9%.
• Have BMI of 25 kg/m2 or above
• Have waist circumference associated with central obesity/metabolic syndrome as per Diabetes Canada definition

• 94cm for males of European, Sub-Saharan African, Eastern Mediterranean and Middle Eastern descent
• 90cm for males of South Asian, Chinese, Japanese, South and Central American descent
• 80cm for females
• No history of stroke, myocardial infarction, or coronary artery disease
• Not wearing implantable device such as a pacemaker, neurostimulators, aneurysm clips, metal fragments, epicardial electrodes, cochlear implants, magnetic ocular implants, penile implants, magnetic tissue expander, some types of breast implants, magnetic orthopedic implants, magnetic dental implants, hearing Aids, intravascular implants, for example VCI filters, coils, stents, cardiac septum implants, ventricular bypass devices.
• Use a CGM in routine diabetes management.

Exclusion criteria

• Major complication within the previous 3 months (e.g., severe hypoglycemia requiring assistance, diabetic ketoacidosis, or cardiovascular event).
• Restriction in aerobic or resistance exercise due to significant diabetes complications (e.g., severe peripheral neuropathy, active proliferative retinopathy, etc.) or other type of limitations (e.g., orthopedic, severe arthritis, etc.).
• Uncontrolled hypertension (e.g., blood pressure >160 mmHg systolic or >100 mmHg diastolic).
• Implanted device, material, or having a condition contraindicated to MRI.
• Ongoing pregnancy or breastfeeding.
• Inability to give consent.
• Use of an injection-based insulin therapy (ex. multiple daily injections or combined pump and injection-based delivery).