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New-Generation Automated Insulin Delivery System for Youth with Type 1

Nov 10, 2018
 

Author: Steve Freed, R.PH., CDE


Study tests new closed-loop control technology using new Control-IQ algorithm.

The achievement of glycemic control remains challenging for patients with type 1 diabetes. So, this study assessed the effectiveness of day-and-night hybrid closed-loop insulin delivery compared with sensor-augmented pump therapy in people with sub-optimally controlled type 1 diabetes who are age 6 years and older.

 

The t:slim X2 insulin pump with Control-IQ Technology (Tandem Diabetes Care) includes a Dexcom G6 sensor and a closed-loop algorithm implemented in the pump that 1) automates insulin correction boluses, 2) has a dedicated hypoglycemia safety system, and 3) gradually intensifies control overnight, aiming for blood glucose levels of approximately 100–120 mg/dL every morning.

In this open-label, multicenter, multinational, single-period, parallel randomized controlled trial, participants were recruited from diabetes outpatient clinics at four hospitals in the UK and two centers in the USA. Patients with type 1 diabetes were randomly assigned aged 6 years and older treated with insulin pump and with suboptimal glycemic control (glycated hemoglobin [HbA1c] 7·5–10·0%) to receive either hybrid closed-loop therapy or sensor-augmented pump therapy over 12 weeks of free living. Allocation to the two study groups was unblinded, and randomization was stratified within center by low (<8·5%) or high (≥8·5%) HbA1c. The primary endpoint was the proportion of time that glucose concentration was within the target range of 70 mg/dL-180 mg/dL (3·9–10·0 mmol/L) at 12 weeks post randomization. Analyses of primary outcome and safety measures were done in all randomized patients.

From May 12, 2016 to Nov 17, 2017, 114 individuals were screened, and 86 eligible patients were randomly assigned to receive hybrid closed-loop therapy (n=46) or sensor-augmented pump therapy (n=40; control group). The proportion of time that glucose concentration was within the target range was significantly higher in the closed-loop group (65%), compared with the control group (54%, mean difference in change 10.8 percentage points, 95% CI 8.2 to 13.5; p<0.0001). In the closed-loop group, HbA1c was reduced from a screening value of 8.3% to 8.0% after the 4-week run-in, and to 7.4% after the 12-week intervention period. In the control group, the HbA1c values were 8.2% at screening, 7.8% after run-in, and 7.7% after intervention; reductions in HbA1c percentages were significantly greater in the closed-loop group compared with the control group (mean difference in change 0.36%, 95% CI 0.19 to 0.53; p<0·0001). The time spent with glucose concentrations below 3.9 mmol/L (mean difference in change −0.83 percentage points, −1.40 to −0.16; p=0.0013) and above 10.0 mmol/L (mean difference in change −10.3 percentage points, −13.2 to −7.5; p<0.0001) was shorter in the closed-loop group than the control group.

In this multinational, multicenter, open-label, randomized trial, it showed that a 12-week use of a day-and-night hybrid closed-loop insulin delivery system, compared with sensor-augmented insulin pump therapy, was associated with an improvement in overall glucose control and a reduction in hypoglycemia risk in sub-optimally controlled type 1 diabetes in children, adolescents, and adults. The hybrid closed-loop system was used safely during daily living without supervision or remote monitoring.

The results showed a 10.8 percentage point increase in time with glucose concentrations within the target glucose range across all age groups. This improvement resulted from a reduction of time spent in hyperglycemia without change in total insulin delivery. A lower amount of bolus insulin and a higher amount of basal insulin in the closed-loop group than in the control group was observed. Lower bolus insulin requirements in the closed-loop group than in the control group could be explained by lower glucose concentrations in this group during closed-loop use, lessening the need for correction boluses. The insulin-to-carbohydrate ratio did not need to be increased, unlike in other closed-loop systems, simplifying clinical adoption of this closed-loop system. Benefits of the closed-loop were greater overnight because, even with the use of a closed-loop system, daytime control is typically confounded by meals and physical activity. These improvements are attributable to the use of the closed-loop system alone because no regular adjustments of insulin pump therapy driven by a health-care professional took place.

From the results, it was concluded hybrid closed-loop insulin delivery improves glucose control while reducing the risk of hypoglycemia across a wide age range in patients with sub-optimally controlled type 1 diabetes.

Practice Pearls:

  • A new algorithm when used with the Dexcom G6 Sensor and a t:slim X2 insulin pump with Control-IQ Technology was able to automate insulin correction boluses.
  • Along with a dedicated hypo safety system, blood glucose levels of approximately 100-120 mg/dL. was able to be maintained every morning.
  • Food boluses still needed to be calculated manually.

Reference:

Sue Brown, Dan Raghinaru, Emma Emory and Boris Kovatchev

Diabetes Care 2018 Oct; dc181249.https://doi.org/10.2337/dc18-1249