Closed-loop Control of Glucose Levels (Artificial Pancreas) During Postprandial Exercise in Adults With Type 1 Diabetes

A Single-blind, Randomized, Cross-over Study to Assess the Efficacy of Single-hormone Closed-loop Strategy at Preventing Hypoglycemia During Unannounced and Announced Exercise in Adults With Type 1 Diabetes

Regular physical activity is associated with many health benefits for individuals with type 1 diabetes including improved cardiovascular fitness and vascular health, decreased insulin requirements, improved body composition and quality of life. However, exercise-induced hypoglycemia is very frequent and thus is the main limiting factor for physical activity practice in this population.

The artificial pancreas is composed of three components: glucose sensor to read glucose levels, insulin pump to infuse insulin and a dosing mathematical algorithm to decide on the required insulin dosages based on the sensor's readings. The artificial pancreas has the potential to reduce the risk of exercise-induced hypoglycemia but the importance of announcing exercise to the artificial pancreas is yet to be explored.

The objective of this study is to investigate 1) if announcing postprandial exercise to the artificial pancreas is beneficial in reducing the risk of hypoglycemia and 2) if an insulin bolus reduction is necessary when announcing the exercise to the artificial pancreas.

Inclusion Criteria:

1. Males and females ≥ 18 years of old.
2. Clinical diagnosis of type 1 diabetes for at least one year.
3. The subject will have been on insulin pump therapy for at least 3 months.
4. Last (less than 3 months) HbA1c ≤ 12%.

Exclusion Criteria:

1. Clinically significant microvascular complications: nephropathy (estimated glomerular filtration rate below 40 ml/min), neuropathy (especially diagnosed gastroparesis) or severe proliferative retinopathy as judged by the investigator.
2. Recent (< 3 months) acute macrovascular event e.g. acute coronary syndrome or cardiac surgery.
3. Use of medication with an effect on heart rate (e.g. beta-blockers).
4. Abnormal blood panel and/or anemia.
5. Ongoing or planned pregnancy.
6. Severe hypoglycemic episode within two weeks of screening.
7. Other serious medical illness likely to interfere with study participation or with the ability to complete the exercise periods by the judgment of the investigator (e.g. orthopedic limitation).
8. Failure to comply with team's recommendations (e.g. not willing to eat snack, not willing to change pump parameters, etc).
9. Problems with venous access.