Assessment of the Efficacy of the Artificial Pancreas Combined With a Qualitative Meal Size Estimation to Control Postprandial Glucose Levels

Institut de Recherches Cliniques de Montreal30 enrolled

Overview

Postprandial glycemic excursions are major determinants of overall glycemic control in type 1 diabetes. Carbohydrate content of ingested meals is the main determinant of post-meal glucose excursion. Accurate carbohydrate counting is a critical aspect of managing postprandial blood glucose levels. accurate carbohydrate counting is considered by patients as a significant burden and frustrating task. The closed-loop system (CLS) 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 objective of this study is to compare the efficacy of two strategies to regulate glucose levels in outpatient settings in adults with type 1 diabetes: 1) single-hormone CLS with rapid acting insulin analogue combined with carbohydrate counting; 2) single-hormone CLS with rapid acting insulin analogue combined with simplified qualitative meal-size estimation. A sub-study will also be proposed to participants. Postprandial exercise combines two situations complicating CLS operation: a high plasma insulin due to insulin on-board related to meal boluses and rapid blood glucose changes (postprandial blood glucose excursion and then drop during exercise) making input from the glucose sensor less accurate. The objective of this sub-study will be to explore the safety and efficacy of the CLS using the combined strategy of pre-meal exercise announcement and meal bolus reduction of 33% when exercise is performed 1 hour compared to 2 hours post meal time.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

NONE

Enrollment

Conditions

Interventions

Single-hormone closed-loop systemDEVICE

Every 10 minutes, the glucose levels as measured by the sensor will be transferred automatically to a LG Google Nexus Smartphone that the algorithm is running on, which will calculate the recommended doses and will send them wirelessly to the infusion pump.

Insulin pumpDEVICE

Tandem Diabetes Care

Continuous glucose monitoring systemDEVICE

Dexcom G6

Aspart or LisproDRUG

Aspart or lispro will be infused with the infusion pump

Carbohydrate countingOTHER

Participants will be required to enter an estimate of the carbohydrate content of their meal into the phone. Insulin boluses will be calculated based on grams of carbohydrates and participant's insulin-to-carbohydrate ratio. Carbohydrate-matching full prandial bolus will be given 5 to 10 minutes before the meal.

Simplified qualitative meal-size estimation strategyOTHER

A pre-meal partial prandial bolus will be given 5-10 minutes before the meal. The partial bolus will be based on the estimated meal size (small, regular, large and extra-large). The closed-loop system will give the remaining insulin needed based on the sensor readings. For this strategy, meal size will be defined as: small as any meal less than 30g, regular meal as any meal between 30g and 60g CHO, large meal as any meal between 60g and 90g CHO, extra-large meal for anything above 90g CHO.

3-week interventionOTHER

Glucose levels will be regulated by the single-hormone closed-loop system for 3 consecutive weeks.

1-hour postprandial exercise (sub-study)OTHER

60 minute exercise will be started one hour after the meal time.

2-hour postprandial exercise (sub-study)OTHER

60 minute exercise will be started two hours after meal time

Exercise announcement and meal bolus reduction (sub-study)OTHER

Meal bolus reduction of 33% at meal time and exercise announcement (increased target glucose from 6 to 9mmolL) to the CLS algorithm

Eligibility

Sex: ALLMin age: 18 Years

Medical Language ↔ Plain English

Inclusion criteria 1. Males and females ≥ 18 years of old. 2. Clinical diagnosis of type 1 diabetes for at least one year. The diagnosis of type 1 diabetes is based on the investigator's judgment; C peptide level and antibody determinations are not needed. 3. The subject will have been on insulin pump therapy for at least 3 months. 4. Currently using, or willing to switch to Lispro U100 or Aspart for the duration of the study. 5. HbA1c \< 10%. Exclusion criteria 1. Clinically significant nephropathy, neuropathy (e.g. known or suspected gastroparesis) or retinopathy (e.g. proliferative retinopathy) as judged by the investigator 2. Recent (\< 6 months) acute macrovascular event e.g. acute coronary syndrome or cardiac surgery 3. Anticipated need to use acetaminophen during interventions with the closed-loop system 4. Pregnancy (ongoing or current attempt to become pregnant) 5. Breastfeeding 6. No nearby third party for assistance if needed (e.g. severe hypoglycemia glucagon treatment) 7. Plans to go abroad or travel at more than 3 hours distance from Montreal during the trial period 8. Severe hypoglycemic episode within two weeks of screening or during the run-in period 9. Severe hyperglycemic episode requiring hospitalization in the last 3 months 10. Current use of glucocorticoid medication (except low stable dose and inhaled steroids) 11. Agents affecting gastric emptying (Motilium®, Victoza®, Ozempic®, Trulicity®, Byetta® and Symlin®) as well as oral anti-diabetic agents (Metformin, Prandase®, 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. 12. Current use of SGLT-2 inhibitors unless at a stable dose for at least 3 months and appropriate ketone testing performed. 13. Known or suspected allergy to the trial products 14. Other serious medical illness likely to interfere with study participation or with the ability to complete the trial by the judgment of the investigator 15. Anticipation of a significant change in exercise regimen between admission and end of the trial (i.e. starting or stopping an organized sport) 16. In the opinion of the investigator, a participant who in unable or unwilling to observed the contraindications of the study devices

Locations (2)

Montreal Clinical Research Institute

Montreal, Quebec, Canada

McGill University Health Center

Montreal, Quebec, Canada

Outcomes

Primary Outcomes

Percentage of time of glucose levels spent between 3.9 and 10.0 mmol/L

Time frame: 504 hours

Relative decrease in glucose levels during exercise compared to pre-breakfast levels (sub-study)

Difference between pre-breakfast levels and the lowest glucose level from the start of the exercise until the end of exercise

Time frame: 3.5 or 4.5 hours

Secondary Outcomes

Percentage of time of glucose levels spent between 3.9 and 7.8 mmol/L

Time frame: 504 hours

Percentage of time of glucose levels spent below 3.9 mmol/L

Time frame: 504 hours

Percentage of time of glucose levels spent below 3.3 mmol/L

Time frame: 504 hours

Percentage of time of glucose levels spent below 2.8 mmol/L

Time frame: 504 hours

Percentage of time of glucose levels spent above 10.0 mmol/L

Time frame: 504 hours

Percentage of time of glucose levels spent above 13.9 mmol/L

Time frame: 504 hours

Percentage of time of glucose levels spent above 16.7 mmol/L

Time frame: 504 hours

Mean glucose levels

Time frame: 504 hours

Fasting glucose levels

Time frame: 504 hours

Standard deviation of glucose levels

Time frame: 504 hours

Standard deviation of insulin delivery

Time frame: 504 hours

Coefficient of variance of glucose levels

Time frame: 504 hours

Coefficient of variance of insulin delivery

Time frame: 504 hours

Between-day variability in glucose levels

Time frame: 504 hours

Between-day variability in insulin delivery

Time frame: 504 hours

Total insulin delivery

Time frame: 504 hours

Number of hypoglycemic events less than 3.1 mmol/L

Time frame: 504 hours

Number of nights with hypoglycemic events less than 3.1 mmol/L

Time frame: 126 hours

Number of days with hypoglycemic events less than 3.1 mmol/L

Time frame: 252 hours

Total number of hours of sensor availability

Time frame: 378 hours

Percentage of time of sensor availability

Time frame: 504 hours

2-hour postprandial glucose levels over the last 3 days of the intervention.

Time frame: 18 hours

Average number of days per participant requiring study team support for at least one technical problem

Time frame: 21 days

Number of hours and percentage of time in open-loop and closed-loop modes

Time frame: 504 hours

Average number of phone calls per participant related to CLS technical issues

Time frame: 504 hours

Decrease in plasma glucose levels during exercise (sub-study)

Difference between glucose levels at the beginning of the exercise and the lowest glucose levels from the start of the exercise until the end of exercise

Time frame: 1 hour

Relative decrease in glucose levels during exercise compared to pre-breakfast levels (sub-study)

Difference between pre-breakfast levels and the lowest glucose level from the start of the exercise until the end of exercise

Time frame: 2 or 3 hours

Percentage of time of plasma glucose levels spent below 3.9 mmol/L (sub-study)