Mobile Closed-Loop Insulin System Lowers Hypoglycemia Risk in Type 1 Diabetes

Smart glucose meter controlled by smartphone
Smart glucose meter controlled by smartphone. Mobile app with blood glucose measurement program. Realistic female belly. Vector illustration
Automated insulin delivery by a mobile closed-loop control system represents a feasible option for glycemic control in type 1 diabetes, with some improvements still needed in device connectivity.

Automated insulin delivery by a mobile closed-loop control (CLC) system represents a feasible option for glycemic control in type 1 diabetes, according to study results published in Diabetes Care.

Insulin pumps with built-in CLC algorithms allow for fine-tuning of insulin delivery by an automated system. Mobile CLC systems controlled by the patient on devices such as smartphones may provide advantages over traditional systems, including accessibility and improved ease of system updates. To determine the feasibility of this system in managing glycemic levels, researchers compared the ability of mobile CLC and sensor-augmented pump (SAP) therapy to reduce the frequency of hypoglycemia in patients with type 1 diabetes.

The multicenter randomized unblinded trial ( Identifier: NCT02985866) included 127 patients (47.2% women; 86.6% white) with type 1 diabetes from 7 university diabetes centers in the United States. Patients were randomly assigned 1:1 to the mobile CLC group (n=65) or the SAP group (n=62). Both groups were provided with a continuous glucose monitoring system that was controlled via Bluetooth connection with a smartphone in the mobile CLC group. Primary outcomes were the percentage of time spent with glucose levels of <70 mg/dL and >180 mg/dL during weeks 3 to 13 of continuous glucose monitor use.

In the mobile CLC group, the median percent time spent in active CLC mode was 69%. The mean percent time spent in the target range (70-180 mg/dL) was higher in the mobile CLC group (64%) compared with the SAP group (57%; P =.0074). The mean percent time spent at <70 mg/dL for the mobile CLC group was 5%±4.2% at baseline and 2.4%±1.7% at follow-up compared with 4.7%±4.9% and 4.0%±3.4% in the SAP group, respectively. The risk-adjusted mean difference between groups was -1.7% (95% CI, -2.4 to -1.0; P <.0001 for superiority).

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The mean percentage of time spent at >180 mg/dL was 40%±17% at baseline and 34%±11% during follow-up in the mobile CLC group compared with 43%±18% and 39%±15%, respectively, in the SAP group, with a risk-adjusted mean difference of -3.0% (95% CI, -6.1 to 0.1, P <.0001 for noninferiority). Secondary hypoglycemic end points (eg, time spent below <54 mg/dL and <60 mg/dL) also occurred less frequently in the mobile CLC group (P <.001 for both).

The benefits of mobile CLC were particularly pronounced at night: comparing the CLC and SAP groups, the mean difference in time spent below 70 mg/dL was -2.3% (P <.0001) during self-reported sleep periods, and the mean difference for time spent above 180 mg/dL was -6.9% (P =.0015). Time spent in the target range overnight was also improved with mobile CLC compared with SAP therapy (mean difference, 6.6%; P =.0002).

The study researchers noted that the use of closed-loop mode in the mobile CLC group was temporarily suspended for up to 2 weeks for some participants because of problems identified with data transfer. In addition, disruptions in wireless signal limited the amount of time the CLC system was active.

“Mobile [CLC] can be an appealing alternative to artificial pancreas systems with control algorithms embedded in the insulin pump, offering certain potential benefits such as more elaborate user interface, portability across devices, and improved user experience,” the researchers noted.

Given the observed superiority in reducing risk for hypoglycemia and noninferiority in exposure to hyperglycemia in their study, the investigators concluded that “mobile CLC is a feasible and promising approach, especially with a more refined system that would ensure better device connectivity.”

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of disclosures.

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Kovatchev B, Anderson SM, Raghinaru D, et al. Randomized controlled trial of mobile closed-loop control [published online January 14, 2020]. Diabetes Care. doi:10.2337/dc19-1310