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Closed-Loop Pump Technical Difficulties Lead to High Rate of Discontinuation

Apr 13, 2019
 
Editor: Steve Freed, R.PH., CDE

Author: Ghazal Blair, Pharm.D. Candidate 2019, LECOM School of Pharmacy

User-friendly devices help increase use by patients.

All individuals with type 1 diabetes and many patients with type 2 diabetes are required to take insulin to manage their blood glucose levels. The main routes of administration most commonly consist of an insulin pump or injection with a needle or pen. Insulin pumps are small computerized devices designed to administer insulin via a thin flexible tube that is inserted subcutaneously. These devices usually deliver insulin either as a continuous steady dose or as a bolus dose, per patient’s demand. Insulin pumps have been used amongst all ages successfully; however, their use has been more popular within young patients with type 1 diabetes.

A previous study assessed the In-home use of the MiniMed™ 670G hybrid closed-loop system for 3 months by adolescents and adults with type 1 diabetes. The results of this trial indicated that using the MiniMed™ 670G hybrid closed-loop system leads to an improvement in HbA1c. Additionally, another study evaluated the glycemic outcomes of in-home use of the same system by children. This study compared the data to those of the adolescent and adult from the previous study and suggested that using the MiniMed™ 670G system improved glycemic outcomes of children with type 1 diabetes, comparable to what was observed for adolescents and adults (P<0.001).

A new observation study has been conducted from 5/30/17 to 9/7/18 at Boston Children’s Hospital on 93 patients (age range 6–25 years) with type 1 diabetes mellitus who chose to be on a Medtronic 670G hybrid closed-loop insulin pump to manage their diabetes. All participants were trained and started on the Medtronic 670G in auto mode. In 2016, the Medtronic MiniMed 670G hybrid closed-loop insulin pump was FDA approved as the first artificial pancreas system for patients with a minimum age of 14 years. In 2018, a broader indication got approved for the system, which includes patients with a minimum age of 7 years. The insulin pump was matched with the Guardian 3 sensor. Although the Medtronic MiniMed 670G hybrid closed-loop insulin pump is FDA cleared to be placed on upper arms and abdomen, the majority of participants placed the device on their stomach area.

This observation trial revealed that 38% (n=35) of participants in the study who used a hybrid closed-loop insulin delivery system discontinued the use of this device within a few months. However, 62% (n=58) of the study participants continued to use the system during the follow-up period (mean follow-up of 8 months). A significant drop from the baseline in HbA1c was noted after six months, among the patients who continued using the Medtronic MiniMed 670G hybrid closed-loop insulin pump. However, it appeared that past the 6-month period, there was a negative effect on HbA1c and causing the HbA1c level to increase. The rise in HbA1c levels caused the HbA1c to no longer be significantly lower than baseline. The HbA1c levels measured during this study are as follows:

  • Average baseline HbA1c: 7.97
  • Average drop in HbA1c within 6 months: 0.27 (P=0.02)
  • Average drop in HbA1C from 6-12 months: 0.18 (P=0.16)
  • Average drop in HbA1C from 12-24 months: 0.03 (P=0.88)

Researchers suggest that the problem staying in auto mode, when using the Medtronic MiniMed 670G hybrid closed-loop insulin pump, seems to be the main issue, leading to the high discontinuation rate. Additionally, frequent alarms, untimely sensor failure, recurrent requirement of calibration, skin adhesion difficulties, and sensor supply issues were other problems that caused participants to stop using the system.

Results showed that the percentage of time spent in auto mode ranged from as little as 10%, up to 90% of the time, within the group of individuals who continued to use the system through the average 8-month follow-up time. Furthermore, an association between the percentage of time spent in auto mode and average HbA1c levels was noted from the data analysis. Participants who spent 57%-74% of time in auto mode and those who have more than 74% of time in auto mode had the most improved HbA1c levels (HbA1c: 7.5-8). Individuals who spent less than 35% of the time in auto mode had an average HbA1c of 8.4%.

This study concluded that the closed-loop insulin delivery in patients with type 1 diabetes who can use the system efficiently causes reduction in HbA1C levels and improves glucose management. Additionally, researchers recommend that because technical difficulties associated with the closed-loop insulin pump systems seem to be the biggest burden for patients, less frequent alarms and fewer exits from auto mode may cause an improvement in the user interface, which eventually leads to more patients continuing to use the system.

Newer updates to improve the MiniMed 670G system have been done since the study, which includes a software update that helps to remove the safety check for a continuous blood glucose entry request in some instances, and a new transmitter that transmits the information from the sensor to the pump.

Practice Pearls:

  • Using the MiniMed 670G system can effectively help manage diabetes for children, adolescents and adults with type 1 diabetes.
  • Approximately 40% of patients who have type 1 and used the closed-loop insulin delivery system quit the system within a few months.
  • Technical difficulties associated with the closed-loop insulin pump systems seem to be the biggest burden for patients.

References:

Goodwin G, et al “Challenges in Implementing Hybrid Closed Loop Insulin Pump Therapy (Medtronic 670g) in a ‘Real-World’ Clinical Setting” ENDO 2019; Abstract OR14-5.

Wood MA, Shulman DI, Pinhas-Hamiel O, et al. Results of MiniMed™ 670G System in-home use: glycemic outcomes of children, adolescents, and adults. Presented at: ENDO 2018: The Endocrine Society Annual Meeting; Chicago, IL; March 17-20, 2018. Abstract SAT-179.

Ghazal Blair, Pharm.D. Candidate 2019, LECOM School of Pharmacy