Using an insulin pump that has an automated delivery function as part of a hybrid closed-loop system may be a good option for people with type 1 diabetes who tend to forget about mealtime bolus doses of insulin, according to a new study presented at the American Association of Clinical Endocrinology 2022 Scientific and Clinical Conference, and described in an article at Healio.
A hybrid closed-loop insulin delivery system involves an insulin pump that is capable of automatically varying the level of basal insulin it delivers, based on a computer algorithm and real-time input from a continuous glucose monitoring (CGM) sensor. It still typically requires manually programming mealtime bolus doses of insulin, based on your current blood glucose level and how you expect your meal to affect that level — although some systems also offer an option for automatic mealtime boluses. The first such system was approved by the U.S. Food and Drug Administration in 2016, and there are now several options available in the United States — including the t:slim X2 insulin pump with Control-IQ technology from Tandem, the MiniMed 670G Hybrid Closed-Loop System from Medtronic, and the Omnipod 5 Automated Insulin Delivery System from Insulet.
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Studies have shown that hybrid closed-loop systems offer benefits and appear to be safe for most people with type 1 diabetes. One recent study showed that for older people with type 1, using a closed-loop system was linked to more consistent blood glucose control than just wearing a CGM system to help with insulin dosing decisions. Another study showed that for younger people with type 1, using a hybrid closed-loop system was linked to more time spent in their target blood glucose range as well as improved quality of life related to diabetes. A previous study also shows that hybrid closed-loop systems appear to be safe and effective for young children with type 1, including when used with less concentrated insulin formulations.
For the latest study, researchers at the University of Colorado looked at the long-term effects of using Tandem’s Control-IQ system in 30 adults with type 1 diabetes. Each of these participants had had diabetes for at least two years prior to the study, had used a CGM system for at least six months, and frequently missed mealtime insulin bolus doses. Typically, the researchers noted, people who often miss mealtime insulin doses aren’t considered good candidates for using a hybrid closed-loop system due to concerns that using the system won’t actually improve their blood glucose control by very much — or that doing so could even present a safety risk.
Participants were randomly assigned to one of three study groups. The “high auto mode” group used only the system’s auto mode to deliver mealtime insulin boluses, never manually programming them. The second group used auto mode 50% to 90% of the time and programmed their own boluses some of the time, while the third group used auto mode less than half the time and often programmed their own boluses.
The researchers collected participants’ CGM and insulin delivery data every three months over the course of 12 months, and used both participants’ routine A1C results (a measure of long-term blood glucose control) and the amount of time they spent in their target glucose range (based on CGM data) to assess the efficacy of using the hybrid closed-loop system. All three study groups started out with an A1C level of 9% or higher, and less than 50% of the time in their target glucose range.
Significant improvements seen in A1C
All three study groups saw a significant reduction in A1c after three months, six months, and 12 months of using the hybrid closed-loop system — in fact, after 12 months, each group had an average A1c reduction of at least 1%, a massive improvement. Time in range also increased by at least 10% in all three groups after 12 months.
At the same time, all three groups experienced a decrease in time spent below their target glucose range — demonstrating that using the hybrid closed-loop system didn’t increase the risk for hypoglycemia (low blood glucose). After 12 months, time below range was just 1.9% for the high auto mode group, 1.8% for the intermediate auto mode group, and 2.0% for the group using auto mode the least.
The researchers concluded that Tandem’s Control-IQ system may be used safely and effectively even in some people who never program their own insulin boluses, even though this isn’t the recommended way to use a hybrid closed-loop system. Future studies, they noted, should look at whether automated insulin delivery systems can lead to similar improvements in other groups of people with type 1 diabetes — such as those with high A1C levels, and those with other health conditions that put them at high risk for poor diabetes-related outcomes.
Want to learn more about A1C? Read “How to Lower A1C Levels Naturally,” “How to Lower Your A1C Levels: More Steps You Can Take” and “HbA1c: What It Is and Why It Matters.”