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Comparative Efficacy of Hybrid Closed-Loop Insulin Delivery Systems and Sensor-Augmented Insulin Pumps in Patients with Type 1 Diabetes

Jan 12, 2019
 
Editor: Steve Freed, R.PH., CDE

Author: Michael Zaccaro, Pharm. D. Candidate 2019, LECOM School of Pharmacy

How does the newest insulin delivery method compare to an established system?

Patients with type 1 diabetes make up a small proportion of the overall population of people who have diabetes. Consequently, there are fewer therapeutic options for people with type 1 diabetes than their counterparts who have type 2 diabetes, thus, adding to the inherent difficulty in achieving and maintaining appropriate glycemic levels. Recently, the hybrid closed-loop insulin delivery systems (sometimes referred to as an artificial pancreas) have become available for clinical use. This is a system in which the information received from a continuous glucose monitoring sensor is analyzed by the insulin pump directly, which then adjusts the dose of insulin without the need for patient involvement. Historically, infusion rates on an insulin pump were made by the patient or a clinician based on the glucose readings and anticipated need. There is evidence to suggest that use of a closed-loop insulin delivery system decreases the likelihood of hypo- and hyperglycemia as well as increases the amount of time the patient is within the normoglycemic range; however, most of the available studies have been of short duration with relatively few participants. This study’s aim was to compare the efficacy of hybrid closed-loop systems with the more commonly used sensor-augmented insulin pump system in patients with type 1 diabetes who had elevated HbA1c  levels.

An open-label randomized controlled trial was selected for the study design in order to determine causality of any observed differences in efficacy. Patients were considered for inclusion as long as they were at least 6 years of age with type 1 diabetes and HbA1c  between 7.5 to 10.0%, and history of insulin pump use for at least 3 months. Patients were excluded if they had a history of hypoglycemic episodes in the past 6 months, reduced or absent hypoglycemic awareness, or use of a continuous glucose monitoring system within the preceding 3 months. Once patients were deemed eligible, patients were randomized (via SAS randomization software) into either the intervention group or the control group. Both groups received a 640G insulin pump, an Enlite 3 glucose sensor, and a Contour Next Link 2.4 glucometer; however, the intervention group’s sensor and pump were programmed to work in tandem as a closed-loop system, whereas the control group’s sensor was used only for monitoring.

Participants were educated about their respective insulin delivery systems during a 4-week run-in period. The outcome of interest was the proportion of time within glucose target range (70 to 180mg/dL). Other measures of glycemic management were measured secondarily (HbA1c, insulin requirements, hypo- and hyperglycemic episodes, etc.). Sensor and insulin pump data was downloaded once weekly. Labs were taken at baseline, then at the start and end of the intervention period. Statistical significance was determined via linear regression model.

Of the 114 patients screened for participation, 86 were deemed eligible and randomized into their respective groups. Baseline characteristics between groups were fairly equivalent with the exception of group size (46 and 40 for intervention and control group respectively). With regards to the primary outcome, the percentage of time the intervention group spent within the glycemic goal range was 10.8% higher than the control group (65 vs 54%, p<0.0001). Likewise, there was a statistically significant difference in HbA1c, in favor of the intervention group (-0.36%, p<0.0001). There was no difference in treatment-related adverse effects between groups.

The results of this study suggest that hybrid closed-loop insulin delivery systems provide more consistent glycemic management than the more commonly used sensor-augmented insulin pumps. However, this study does not address the disadvantages of insulin pump use. For instance, insulin pumps of either variety require extensive patient education in order to maintain properly. Additionally, the price of the pump may be cost-prohibitive in certain circumstances. Thus, appropriate patient selection becomes an integral step in the effective use of either system. While the hybrid closed-loop insulin delivery system may provide a benefit over the sensor-augmented insulin pumps, this finding is only clinically relevant in appropriately selected patients.

Practice Pearls:

  • Hybrid closed-loop insulin delivery systems appear to provide more consistent glycemic management when compared to sensor-augmented insulin pumps.
  • Hybrid closed-loop insulin delivery systems have similar safety profiles to traditionally utilized insulin pumps.
  • Appropriate patient screening and selection is an integral step in the use of any insulin delivery system.

Reference:

Tauschmann. M., et al. “Closed-loop insulin delivery in suboptimally controlled type 1 diabetes: a multicentre, 12-week randomised trial.” Lancet, vol. 392, 2018, pp. 1321-1329., doi:10.1016/S0140-6736(18)31947-0

Michael Zaccaro, Pharm. D. Candidate 2019, LECOM School of Pharmacy