Tandem auto-bolusing artificial pancreas has greatest impact on highest glucose levels: study

Tandem Diabetes Care has already proven that its closed-loop system for automated insulin delivery can improve the amount of time spent in range for people of all ages with Type 1 diabetes, but a new study attributes some of the strongest improvements in those results to the system’s automatic correction bolusing capabilities.

Tandem’s Control-IQ algorithm connects the company’s own insulin pumps to Dexcom’s continuous glucose monitors. A user’s CGM transmits real-time blood sugar readings to the algorithm, which analyzes the measurements and predicts how they might change within the next 30 minutes, then automatically adjusts the pump’s dosing information as necessary.

The Control-IQ artificial pancreas system also offers auto-bolusing to people with diabetes who use Tandem’s t:slim X2 insulin pump. If the algorithm predicts—or the connected CGM detects—an especially high spike in the user’s blood sugar, the system can send out a correction dose of insulin up to once an hour to prevent hyperglycemia.

A study of the Control-IQ system that was published in 2019, before its FDA approval later that year, followed 168 participants with Type 1 diabetes who were aged 14 and older and who were assigned to use either Tandem’s closed-loop system or a non-automated combination of a CGM and insulin pump. By the end of the six-month study, the Control-IQ users saw the amount of time they spent in a healthy glucose range improve by an average of 2.6 hours per day, while the control group registered no improvements to time in range.

A new analysis published in Diabetes Technology & Therapeutics this month suggests not only that the boosts to time in range may actually be even greater for a wider pool of users, but also that those with the highest blood sugar levels before beginning use of the Control-IQ algorithm may see the most benefits from the auto-bolusing feature.

The analysis looked at three randomized, controlled trials, the results of which were published in 2019, 2020 and March of this year. Altogether, they included 369 participants between the ages of 2 and 72, 256 of whom were assigned to use the Control-IQ system, comprising the t:slim X2 insulin pump and a Dexcom G6 CGM.

After three months, on average, the Control-IQ group saw their time in range grow from 57% at baseline to 70%, while the control group’s time increased only from 56% to 57%. That represents an additional two-and-a-half to three hours that the experimental group spent in a healthy glucose range per day, compared to those in the control group.

Additionally, the researchers noted that the participants who had the highest glucose levels at the start of the study saw the most dramatic improvements in both their HbA1c and time in range after using the Control-IQ algorithm to help manage their diabetes.

The study’s authors attributed those improvements in large part to the algorithm’s automatic bolusing capabilities, writing, “The greatest benefit was observed in participants with the worst baseline glycemic control, in whom the auto-bolus feature of the Control-IQ algorithm appears to have substantial impact.”

In an announcement this week regarding the analysis’ results, Roy Beck, M.D., Ph.D., executive director of the Jaeb Center for Health Research, explained, “The high number of automatic boluses given by the system in this group likely reflect previously missed meal boluses or lack of manual correction boluses when on conventional therapy and demonstrates the substantial impact Control-IQ technology’s auto-bolusing feature can have for people struggling on a standard pump or multiple daily injections.”