Insulin Pump Shown Difficult for Many Users

MiniMed 670G system (Medtronic Inc.)

25 Mar. 2019. An assessment of a closed-loop insulin pump system shows a sizeable proportion of first-time users stopped using its automated feature because of problems in making it work. A team from Boston Children’s Hospital reported their findings yesterday at the annual meeting of the Endocrine Society in New Orleans.

Researchers led by endocrinologist Gregory Goodwin, also a professor of pediatrics at Harvard Medical School, sought real-world evidence on the practical utility of the Medtronic MiniMed 670G, a closed-loop hybrid insulin pump system, sometimes called an artificial pancreas. The Food and Drug Administration in September 2016 cleared the MiniMed 670G for marketing to people age 14 and up — later extended to children as young as 7 — with type 1 diabetes, an inherited autoimmune disorder where the body does not produce insulin, and is diagnosed primarily in children or young adults. About 1.25 million people in the U.S. have type 1 diabetes, about 5 percent of people with diabetes of any kind.

The MiniMed 670G is called an artificial pancreas because it can monitor glucose levels and adjust insulin flow with little or no intervention by the wearer. However, people wearing the device still may need to manually increase an insulin dose to account for carbohydrate increases at meal times, and periodically calibrate the sensor. The system monitors glucose levels with the sensor attached to the body, and pumps insulin through an infusion patch and catheter, while an algorithm controls the device, keeping glucose levels in personalized target range.

Despite being hailed as a “groundbreaking” and “life-changing” development, anecdotal evidence persists about the MiniMed 670G’s difficulty to use, particularly in auto-mode where the system automatically adjusts insulin flow to correspond to the wearer’s glucose levels. Goodwin and colleagues reviewed the experiences of 83 children and young adults, age 6 to 25 — most were teenagers — who tried the MiniMed 670G for the first time, in May to September 2018. All of the participants in the study previously used insulin pumps or were familiar with continuous glucose monitoring, and were trained by company representatives in the system’s use.

The team reports nearly 1 in 5 participants, 16 individuals or 19 percent, stopped using the MiniMed 670G in auto-mode during this time. The main reasons for discontinuing auto-mode features were technical difficulties with the sensor or keeping the device in auto-mode, with the system forcing exits on occasion. Other reasons cited were calibration requirements, problems with sensor durability or adhesion, and skin irritation. The remaining 67 participants or 81 percent continued to use auto-mode, although the percent of time with this feature ranged from 10 to 90 percent.

The researchers followed-up with 58 of the 67 auto-mode users and found they benefited from the MiniMed 670G. Blood glucose levels from the participants’ hemoglobin a1c data showed an average decrease of 0.27 percent after 97 days, compared to readings taken in the 6 months before starting on the system, a difference large enough for statistical reliability.

“Patients can reap the full benefits of the system in auto-mode,” says Goodwin in an Endocrine Society statement. “But this technology is demanding and requires a technically sophisticated patient or parent to use it.”

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