Safety of Overestimation of a Meal Insulin Bolus in the Context of Dual-hormone Closed-loop Operation - Part 2

Institut de Recherches Cliniques de Montreal

Status and phase: Completed; Phase 2

Conditions: Type 1 Diabetes

Treatments: Drug: Insulin; Device: Dexcom G4 Platinum glucose sensor; Other: Dual-hormone closed-loop; Device: Accu Chek Combo insulin pump; Drug: Glucagon

Study type: Interventional

Funder types: Other

Identifiers

NCT02798250

CLASS-Safety study - Part 2

Details and patient eligibility

About

In previous studies, investigators have studied if a pre-meal insulin bolus based on estimated carbohydrate meal size would alleviate the burden of carbohydrate counting without a significant degradation in postprandial glucose control. With this strategy, the patient would only have to evaluate the size of the meal in terms of carbohydrate (snack, regular, large or very large). It is however important to establish the safety of this simplified meal bolus approach. The safety of overestimating a meal insulin bolus in the context of closed-loop strategy needs to be assessed. For ethical reasons, only dual-hormone closed-loop will be tested.

Investigators hypothesize that dual-hormone closed-loop with overestimated meal size bolus will not increase time below 4.0 mmol/L compared to dual-hormone closed-loop with an adequately estimated meal size bolus.

Enrollment: 11 patients

Sex: All

Ages: 18+ years old

Volunteers: No Healthy Volunteers

Inclusion criteria

1. Males and females ≥ 18 years 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 and currently using a fast acting insulin analog (Lispro, Aspart or Glulisine).
4. Last (less than 3 months) HbA1c ≤ 10%.
5. Currently using carbohydrate counting as the meal insulin dose strategy.

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. Pregnancy.
4. Severe hypoglycemic episode within 1 month of screening.
5. Agents affecting gastric emptying (Motilium®, Prandase®, Victoza®, Byetta® and Symlin®) as well as oral anti-diabetic agents (Metformin, SGLT-2 inhibitors and DPP-4 inhibitors) if not at a stable dose for 3 months. Otherwise, these medications are acceptable and will be kept stable during the entire protocol.
6. Oral steroids unless patients present a low stable dose (e.g. 10 mg or less of prednisone per day or physiological doses, less than 35 mg/day, of hydrocortisone Cortef®). Inhale steroids at stable dose in the last month are acceptable.
7. Other serious medical illness likely to interfere with study participation or with the ability to complete the trial by the judgment of the investigator (e.g. unstable psychiatric condition).
8. Failure to comply with team's recommendations (e.g. not willing to change pump parameters, follow algorithm's suggestions, etc).

Trial design

Primary purpose: Treatment

Allocation: Randomized

Interventional model: Crossover Assignment

Masking: Single Blind

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11 participants in 2 patient groups

Dual-hormone CL with overestimation of meal size category

Active Comparator group

Description:

A regular size standardized meal of 45g of carbohydrates will be provided to the patient and the meal size will be overestimated by one category, which will result in a meal insulin bolus for a meal of 65g of carbohydrates.

Treatment:

Device: Dexcom G4 Platinum glucose sensor

Drug: Insulin

Drug: Glucagon

Other: Dual-hormone closed-loop

Device: Accu Chek Combo insulin pump

Dual-hormone CL with adequate estimation of meal size category

Active Comparator group

Description:

A regular size standardized meal of 45g of carbohydrates will be provided to the patient and the meal size will be adequately estimated, which will result in a meal insulin bolus for a meal of 35g of carbohydrates.

Treatment:

Device: Dexcom G4 Platinum glucose sensor

Drug: Insulin

Drug: Glucagon

Other: Dual-hormone closed-loop

Device: Accu Chek Combo insulin pump