Can hybrid closed-loop insulin delivery improve control of diabetes?

This study compared hybrid closed-loop (HCL) insulin delivery to an insulin pump or daily injections for adults with type 1 diabetes (T1D). It found that an HCL system led to better glucose control and a more positive experience of managing diabetes.

For many patients with T1D, managing blood glucose (sugar) levels is a daily challenge. The body cannot create the hormone insulin, which directs body tissues to absorb glucose (sugar) from the blood. Instead, patients monitor their own blood glucose through finger stick tests and use injections of artificial insulin or an automatic insulin pump. However, most patients with T1D do not maintain the recommended blood glucose targets. Additionally, carefully planning meals and exercise to manage blood glucose can be psychologically exhausting.

Hybrid closed-loop (HCL) insulin delivery connects a continuous glucose monitor directly to an insulin pump. This system automatically adjusts baseline insulin levels, so the patient does not need to monitor levels as closely. However, the patient manually adjusts insulin before eating or exercise. This system can also reduce overnight episodes of hypoglycemia (abnormally low glucose).

Most studies of HCL have compared them to sensor-augmented pumps. It is not clear how HCL performs when transitioning from finger stick monitoring, which is still used by most adults with T1D. Also, it is not clear how HCL affects the psychological aspects of diabetes management.

This study included 120 adults with T1D. Half of the participants (51%) normally used multiple daily insulin injections to control their diabetes, and the others used an insulin pump. Prior to the trial, participants used finger stick monitoring to test glucose levels. The researchers randomly assigned 61 participants to use HCL, and the other 59 continued with their usual method. All participants were followed for 26 weeks.

The HCL group had well-controlled glucose levels a significantly larger percentage of the time (70% vs. 55%). The two groups started out with the same amount of time with well-controlled glucose levels (55% vs. 55%). Both patients who used daily injections and an insulin pump had similar benefits from switching to HCL. However, patients who started out using injections required longer to adjust to the HCL system (28 vs. 14 days).

Participants were given a survey of quality of life related to diabetes management. The HCL group reported better well-being related to diabetes. Neither group experienced a change in treatment satisfaction or sleep quality.

This trial found that HCL improves glucose control and diabetes-related quality of life for patients with T1D.

Researchers spent more time with HCL participants (27 vs. 14 hours). Time spent with health care providers can improve patients’ mindsets and medical outcomes, which is part of the “placebo effect.”