Artificial pancreas bests smart insulin pump for glycaemic control in T1D

Use of a closed-loop system, also known as artificial pancreas, led to better glycaemic control in terms of more time spent in the target glycaemic range than a sensor-augmented insulin pump in patients with type 1 diabetes (T1D), according to the iDCL* study.

“It is clear that patients would appreciate wearing devices that require minimal interaction, leading to a more carefree lifestyle,” wrote Dr Daniela Bruttomesso from the University of Padua, Padua, Italy in a linked editorial. [N Engl J Med 2019;381:1774-1775]

The new closed-loop system, according to the investigators, relies on “an algorithm with a dedicated hypoglycaemia safety module, automated correction boluses, and overnight intensification of basal insulin delivery designed to consistently target near-normal glycaemia each morning.”

More time in target range

Patients receiving the closed-loop system spent significantly more time within the target glucose range (70–180 mg/dL), which improved from 61 percent to 71 percent, compared with the control group using a sensor-augmented pump who saw their time within target range unchanged (59 percent) during the 6 months study. This translates to a 11-percentage points greater time within target range with the closed-loop system vs the control pump (p<0.001). [N Engl J Med 2019;381:1707-1716]

“[The 11-percentage points difference is] an advantage that amounted to 2.6 hours per day … less time in hyperglycaemia [2.4 hours less/day] and hypoglycaemia [13 minutes less/day],” explained the researchers.

“Beneficial glycaemic effects associated with the closed-loop system were seen during both daytime and nighttime and were particularly prominent in the second half of the night,” they observed. “[Furthermore,] the glycaemic benefits associated with closed-loop control were seen in the first month of the trial and were sustained over the entire 6 months.”

The results were consistent across a wide range of patients with different age and regardless of whether they were insulin-pump or injection insulin users.    

Bruttomesso commended the results as “impressive and clinically relevant,” since a recent study has shown that each 10 percent less time spent in the target glucose range was associated with 64 percent increased risk of retinopathy development/progression and 40 percent increased risk of microalbuminuria. [Diabetes Care 2019;42:400-405]

The multicentre study randomized 168 T1D patients aged 14–71 years (mean age 33 years) to receive closed-loop system or a sensor-augmented pump in a 2:1 ratio.

Main secondary outcomes including the percentage of time having glucose level >180 mg/dL, glycated haemoglobin level, mean glucose level, and percentage of time that the glucose level was <70 mg/dL or <54 mg/dL were all significantly different between the two groups, in favour of the closed-loop system.

Specifically, the percentage difference between treatments was -0.88 percent (p<0.001) for time spent having glucose level <70 mg/dL and -0.33 percent (p=0.001) for glycated haemoglobin levels, both favouring the closed-system.

For the closed-loop group, the system was reported to be in closed-loop mode 90 percent of the time during the 6 months.

There were more adverse events (AEs) in the closed-loop group compared with the control group, mainly due to hyperglycaemia with ketosis resulting from pump infusion set failure.

A big step forward

“The closed-loop system is becoming a mature technology ready for practical use, but there are a variety of barriers to a fully automated closed-loop system,” said Bruttomesso. “Whether closed-loop systems can be used in higher-risk patients, such as those with impaired awareness of hypoglycaemia, also remains a pressing issue.”

“We are not there yet, but the trial by Brown et al. offers an almost fingerstick-free option, providing a big step toward a brighter future for patients.”