The Endocrine Society

The Endocrine Society

March 23, 2019
2 min read

Technology snags may limit adoption of current hybrid closed-loop insulin delivery system

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NEW ORLEANS — Nearly one-third of participants in a study of first-time users of an “artificial pancreas” stopped using the system within a few months, primarily because of difficulties with the technology, according to data presented at The Endocrine Society Annual Meeting.

Those who continued using the Medtronic MiniMed 670G, the only FDA-approved hybrid closed-loop insulin delivery system on the market, experienced a mean decrease in HbA1c at 6 months, according to a presenter.

Gregory Goodwin

“The main takeaway message is that hybrid closed-loop technology is very challenging for patients to successfully implement as it currently exists,” Gregory Goodwin, MD, senior associate physician in medicine at Boston Children’s Hospital and assistant professor of pediatrics at Harvard Medical School, told Endocrine Today.

The MiniMed 670G consists of a continuous glucose monitor that measures glucose levels every 5 minutes and an insulin pump and infusion patch to deliver basal insulin in response to glucose levels, referred to as “automode.” Users must calibrate the CGM with finger-stick measurements, and manually request insulin doses to counter mealtime carbohydrate consumption.

Goodwin and colleagues prescribed the MiniMed 670G to 83 patients with type 1 diabetes (age range, 6-25 years) between May 2017 and September 2018. Until June 2018, the system was approved for use only by patients aged at least 14 years, so most participants were teenagers. Participants had prior experience with insulin pumps and CGM, and a Medtronic representative trained them on the study system.

“Over 30% of our patients stopped using the technology, most within 3 months after starting therapy,” Goodwin said.

Ultimately, the dropout rate was 38%, Goodwin said during a press briefing.

Those who completely stopped using the automode function (19%) mostly reported difficulties with the glucose sensor, such as problems with calibrations, sensor durability or skin issues, or with forced exits, according to Goodwin.

“Automode means that this is the artificial pancreas system where it’s delivering insulin based on glucose level. What happens is if you don’t fulfill certain requirements — if you’re high for too long — it kicks you out of automode, and you’re back to using a standard insulin pump,” Goodwin said during the briefing.

The remaining participants continued to use the automode function from 10% to 90% of the time.

Among participants who continued with the system and had HbA1c data available for the 6 months leading up to the study, researchers observed a mean 0.27% decrease in HbA1c at 6 months (P = .025). However, the decrease did not persist between 6 and 12 months or between 12 and 24 months, Goodwin said.


“[ENDO] attendees may find this data not as encouraging as the well-controlled short-term hybrid closed-loop studies published in the literature to date,” Goodwin told Endocrine Today. “However, this is the first-generation hybrid closed-loop technology, and we feel that efforts to make this technology more 'user friendly' will likely result in patients being able to reap the benefits of hybrid closed-loop technology in the future.” – by Jill Rollet


Goodwin G, et al. OR14-5: Challenges in implementing hybrid closed loop insulin pump therapy (Medtronic 670g) in a ‘real world’ clinical setting. Presented at: The Endocrine Society Annual Meeting; March 23-26, 2019; New Orleans.

Disclosure: Goodwin reports no relevant financial disclosures.