Closed-loop trumps sensor-augmented pumps for older T1D patients

A closed-loop insulin delivery system is both effective and safe for the management of type 1 diabetes (T1D) in older adults, according to a recent study. As compared with sensor-augmented pump systems, closed-loop deliveries yield greater time-in-range (TIR) outcomes and help minimize time spent in hypoglycaemic range overnight.

“Our randomized trial showed 75-percent TIR with closed-loop insulin delivery, an improvement of 6 percentage points over sensor-augmented pump when accounting for period effect,” the researchers said. “A key strength of our study is the investigation of older adults with T1D, a group among whom little was previously known about closed-loop effects.”

Thirty T1D patients (mean age 67 years, 63 percent women) were enrolled in the present open-label, randomized, crossover trial. Participants received either the closed-loop or the sensor-augmented pump interventions, which they used for a duration of 4 months before crossing over to the alternative insulin delivery system. The primary outcome of interest was TIR (3.9–10.0 mmol/L), as determined by continuous glucose monitoring (CGM).

The closed-loop pump yielded better CGM metrics, with significantly higher TIR than the sensor-augmented devices (75.2 percent vs 69.1 percent; difference, 6.2 percentage points, 95 percent confidence interval [CI], 4.4–8.0; p<0.0001). In absolute terms, such difference corresponded to 90 minutes more per day in TIR with the closed-loop system. [Diabetes Care 2021;doi:10.2337/dc21-1667]

Similarly, the time with CGM >10.0 mmol/L was lower by 5.4 percentage points in the closed-loop vs sensor-augmented delivery systems (95 percent CI, 3.5–7.3; p<0.0001), corresponding to an absolute difference of 78 minutes per day.

Moreover, the time below the hypoglycaemia thresholds of 3.9, 3.3, and 3.0 mmol/L was lower with the closed-loop vs sensor-augmented pump.

The researchers found that such differences between closed-loop and sensor-augmented pumps were more pronounced when using overnight measurements. For instance, mean TIR overnight was 86.9 percent with the closed-loop system, as opposed to only 76.8 percent with sensor-augmented devices. The resulting difference was statistically significant (10.1 percentage points, 95 percent CI, 6.9–13.4; p<0.0001).

A similar pattern was reported for time in hypoglycaemia, with closed-loop devices yielding shorter durations below all thresholds (3.9, 3.3, and 3.0 mmol/L) than the sensor-augmented comparator.

In terms of safety, the researchers documented no serious adverse events while using the closed-loop pump. In contrast, two complications arose when using the sensor-augmented devices, including one episode of diabetic ketoacidosis and vitreous haemorrhage. Five severe hypoglycaemia episodes occurred, three of which were during the closed-loop phase. There were no associated hospitalizations or hypoglycaemia-related seizures.

“Closed-loop insulin delivery had its greatest benefit overnight, improving the proportion of time spent within, above, and below CGM target range. Of particular clinical importance among this older cohort was the fourfold reduction in the time overnight spent below all hypoglycaemia thresholds with closed loop,” the researchers said.

“Further research is needed to examine the effects and safety of closed loop among people with frailty or major cognitive impairment and among individuals with less favourable pre-existing glycemia,” they added.