Closed loop system delivers better glycaemic control: trial

Six month results from a trial of a closed-loop insulin delivery system have shown that it improved glycemic outcomes in patients with type 1 diabetes (T1D).

Published in the NEJM, results from the International Diabetes Closed-Loop (iDCL) Study showed that use of a closed-loop system (Control-IQ, Tandem Diabetes Care) led to a greater percentage of time that the glucose level was in target range, less hyperglycaemia and hypoglycaemia, and better HbA1c levels than a sensor-augmented pump.

The trial enrolled 168 people age 14 or older with T1D and HbA1c ranging from 5.4 to 10.6%. Participants were randomly assigned to use either the artificial pancreas system called Control-IQ or sensor-augmented pump (SAP) therapy with a CGM and insulin pump that did not automatically adjust insulin throughout the day.

Over the course of the trial, the users of the artificial pancreas system significantly increased the amount of time with their blood glucose levels in the target range of 3.9 to 10.0 mmol/L by an average of 2.6 hours per day, while the time in range in the control group remained unchanged.

The mean percentage of time that the glucose level was within the target range increased in the closed-loop group from 61±17% at baseline to 71±12% during the 6 months and remained unchanged at 59±14% in the control group.

Results for the main secondary outcomes (percentage of time that the glucose level was >10.0 mmol/L, mean glucose level, HbA1c level, and percentage of time that the glucose level was <3.9mmol/L  or <3.0 mmol/L) all favoured the closed-loop system.

The mean adjusted difference in HbA1c after 6 months was −0.33 percentage points (95% CI, −0.53 to −0.13; P=0.001). In the closed-loop group, the median percentage of time that the system was in closed-loop mode was 90% over 6 months.

No serious hypoglycaemic events occurred in either group; one episode of diabetic ketoacidosis occurred in the closed-loop group.

The study investigators said it was notable that the closed loop system was used in day to day living conditions and there was high adherence to device use in both groups.

They said an advantage of closed loop device was a special safety module dedicated to prevention of hypoglycaemia, and there was gradually intensified control overnight to achieve near-normal blood sugar levels every morning.

“This study in particular demonstrates tight blood sugar control overnight so a person can wake up with a blood sugar level close to normal most mornings,” said study co-lead author Sue A. Brown, MD, from University of Virginia.

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