Type 1 diabetes patients using closed-loop system spent more time in glucose target range than peers in control

A study published in the New England Journal of Medicine found that patients had an average of 2.6 more hours a day in their target glucose range compared to their peers using a sensor-augmented pump.
By Laura Lovett
01:38 pm

A study published in the New England Journal of Medicine found that Type 1 diabetes patients using a closed-loop system spent a higher percentage of time in their target glucose range than their peers using a sensor-augmented pump. 

Researchers also found that the glycated hemoglobin level of patients using the closed-loop system improved during the study. Conversely, on average patients in the control group experienced no change, according to the study, which was funded by the National Institute of Diabetes and Digestive and Kidney Diseases.


Learn on-demand, earn credit, find products and solutions. Get Started >>

During the six-month trial, participants that used the closed-loop system increased time in their target glucose level from 61±17% at baseline to 71±12%. However, the control group, which used the sensor-augmented pump, on average had no gains from baseline. 

“The percentage of time that glucose was in the target range of 70 to 180 mg per deciliter over the six-month period, as measured by continuous glucose monitoring, was 11 percentage points higher among patients with the closed-loop system than among those with a sensor-augmented pump, an advantage that amounted to 2.6 hours per day,” researchers said.  

Scientists also found that during the day, 70% of participants in the closed-loop system group were in the glucose level target range, and 59% of the control group were in this range. At night, 76% of the closed-loop system users and 59% of control group were in the target range. 

The authors of the report noted that this improvement impacted closed-loop system users from a variety of demographics. 

“The percentage of time that the blood glucose level was within the target range of 70 to 180 mg per deciliter or below 70 mg per deciliter consistently favored the closed-loop system across a broad range of baseline characteristics, including age, sex, body-mass index, income, educational level, insulin pump or injection use, previous use of a continuous glucose monitor and glycated hemoglobin level, and the results were consistent across the seven clinical centers,” researchers wrote. 

In addition to target range, researchers reported the adjusted difference in glycated hemoglobin levels after six-months was roughly a third of a percentage point lower in patients with the closed-loop system, which analysis revealed to be a significant decline. 

It is important to note that more adverse effects were seen in the closed-loop system than the control group. Researchers said this was mainly a result of “hyperglycemia with ketosis from pump infusion set failure.”


The study included 168 participants with Type 1 diabetes between the ages of 14 to 71. Participants were randomly assigned a group, with two-thirds of participants sorted into the closed-loop system and one third into the control group. 

The amount of time that patients have lived with diabetes ranged from one year to 62 years. Participants’ baseline glycated hemoglobin ranged from 5.4 to 10.6%. All of the participants finished the trial. Researchers reported a 100% follow up visits and 99.9% of telephone contacts were completed. 


Closed-loop systems — commonly referred to as an “artificial pancreas” — combine a continuous glucose monitor and an insulin pump to regulate a user’s insulin with minimal interaction required from the patient. 

The technology has become a hot topic in digital health, despite still being relatively new. 

“Currently, one closed-loop system, the Medtronic MiniMed 670G, is in commercial use in the United States, but randomized trials are needed to assess its efficacy and safety,” researchers wrote. “Such a system, which modulates basal insulin delivery but does not administer automated boluses, is referred to as a 'hybrid' closed-loop system.”

This isn’t the first study on closed-loop systems. In 2018 the Lancet published an article, which found Type 1 diabetes patients using a hybrid closed-loop artificial pancreas therapy demonstrated improved glucose control and lower risk of hypoglycemia compared to those managing their own glucose levels with an insulin pump and continuous glucose monitor.


“Over a six-month period, the closed-loop system used in our trial led to a greater percentage of time that the glucose level was in a target range, less hyperglycemia and hypoglycemia, and better glycated hemoglobin levels than a sensor-augmented pump,” the researchers wrote. 



The latest news in digital health delivered daily to your inbox.

Thank you for subscribing!
Error! Something went wrong!