Inclusion Criteria:  Males and females aged between 18 and 65 years old. Clinical diagnosis of type 1 diabetes for at least five years. Treatment with multiple daily insulin injections or insulin pump therapy and using insulin analogs (rapid, ultra-rapid or basal). The type of insulin should be stable for at least 1 month. Participants not using an insulin analog will be offered the opportunity to switch to an insulin analog and this will be done at least 1 month before inclusion. Impaired awareness of hypoglycemia (Gold score ≥ 4). HbA1c ≤ 10% Using a continuous glucose monitor or being willing to start using one for the study Having an electronic device supporting the Polar Beat application (heart rate monitor).  Exclusion Criteria:  Clinically significant microvascular complications: nephropathy (estimated glomerular filtration rate below 40 ml/min), neuropathy (especially advanced peripheral neuropathy with significantly lower limb reduced proprioceptive perception) or severe proliferative retinopathy as reported by the patient and/or judged by the investigator. High risk foot problem (e.g., previous amputation, history of foot wound, known severe neuropathy or peripheral arterial disease) Recent (< 3 months) acute macrovascular event e.g., acute coronary syndrome or cardiac surgery or history of significant heart disease. Known significant cardiac rhythm abnormality based on investigator judgment. Abnormal blood panel and/or anemia (Hb < 100g/L). Ongoing pregnancy or breastfeeding. Severe hypoglycemic episode or diabetic ketoacidosis within 1 month of screening. Taking any medication that affects heart rate (e.g., beta-blockers). Uncontrolled hypertension (blood pressure >160/100 mm Hg). Uncontrolled angina. Treatment with oral steroids within the last 3 months. History of significant lung disease that would limit exercise. Seizure within the last 3 months. Participation in high-intensity interval training (or equivalent) in the past 6 months. Physical ability preventing the completion of the 12-week training program (e.g., orthopedic limitation). Inability to give consent.