Original Research

Real-World Experience With Automated Insulin Pump Technology in Veterans With Type 1 Diabetes

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Background: Advancements in diabetes technology now allow insulin pump and continuous glucose monitor (CGM) technology to be a part of usual US Department Veterans Affairs (VA) clinical care. The automated insulin pump (AIP) delivers insulin automatically based on CGM readings. In randomized clinical trials the closed-loop system has shown to improve glycemic control in children and younger adults with type 1 diabetes mellitus (T1DM) while preventing hypoglycemia. However, its safety and efficacy is less well known in older veterans with T1DM. In this VA pilot study, we aimed to assess AIP technology in the real world of an older population of veterans with T1DM followed in the outpatient setting.

Methods: Thirty-seven patients with T1DM new to AIP seen at the Malcom Randall VA Medical Center in Gainesville, Florida, were evaluated between March and December of 2018 on an Medtronic Minimed 670G Insulin Pump System. We collected demographic as well as clinical data before and after the initiation of AIP, including standard insulin pump/CGM information (sensor wear, time in target glucose range, time in automated mode, other).

Results: At the time of the initiation of AIP, the mean (SD) age of patients was 59.1 (14.4) years; 35 identified as male and 2 as female. The mean (SD) duration of T1DM was 25.3 (12.0) years. Patients transitioned from either insulin injections or other non-AIP pump to AIP safely—there was no increase in hypoglycemia, and the mean (SD) hemoglobin A 1c decreased from 7.6% (0.8) to 7.3% (0.80) by the second follow-up visit.

Conclusion: In this real-world study, AIP use was both safe and viable as a tool for T1DM management with older veterans. This technology further engaged veterans in monitoring their blood sugars and achieving more optimal glycemic control. Future long-term, larger studies are much needed in this setting.


 

References

Insulin pump technology has been available since the 1970s. Innovation in insulin pumps has had significant impact on the management of diabetes mellitus (DM). In recent years, automated insulin pump technology (AIP) has proven to be a safe and effective way to treat DM. It has been studied mostly in highly organized randomized controlled trials (RCTs) in younger populations with type 1 DM (T1DM).1-3

One of the challenges in DM care has always been the wide variations in daily plasma glucose concentration that often cause major swings of hyperglycemia and hypoglycemia. Extreme variations in blood glucose have also been linked to adverse outcomes, including poor micro- and macrovascular outcomes.4,5 AIP technology is a hybrid closed-loop system that attempts to solve this problem by adjusting insulin delivery in response to real-time glucose information from a continuous glucose monitor (CGM). Glucose measurements are sent to the insulin pump in real time, which uses a specialized algorithm to determine whether insulin delivery should be up-titrated, down-titrated, or suspended.6

Several studies have shown that AIP technology reduces glucose variability and increases the percentage of time within the optimal glucose range.1-3,7 Its safety is especially indicated for patients with long-standing DM who often have hypoglycemia unawareness and recurrent episodes of hypoglycemia.7 Safety is the major advantage of the hybrid closed-loop system as long duration of DM makes patients particularly prone to emergency department (ED) visits and hospitalizations for severe hypoglycemia.8 Recurrent hypoglycemia also is associated with increased cardiovascular mortality in epidemiologic studies.9

Safety was the primary endpoint in the pivotal trial in a multicenter clinical study where 124 participants (mean age, 37.8 years; DM duration, 21.7 years; hemoglobin A1c [HbA1c], 7.4%) were monitored for 3 months while using a hybrid closed-loop pump, similar to the one used in our study.10 Remarkably, there were no device-related episodes of severe hypoglycemia or ketoacidosis. There was even a small but significant difference in HbA1c (7.4% at baseline, 6.9% at 3 months) and of the time in target range measured by CGM from 66.7% at baseline to 72.2% at 3 months). However, the mean age of the population studied was young (mean age, 37.8 years). It is unclear how these results would translate for a population of older patients with T1DM. Moreover, use of AIP systems have not been systematically tested outside of carefully controlled studies, as it would be in middle-aged veterans followed in outpatient US Department of Veterans Affairs (VA) clinics. Such an approach in the context of optimal glucose monitoring combined with use of structured DM education can significantly reduce impaired awareness of hypoglycemia in patients with T1DM of long duration.11

This is the first study to assess the feasibility of AIP technology in a real-world population of older veterans with T1DM in terms of safety and acceptability, because AIP has just recently become available for patient care in the Veterans Health Administration (VHA). This group of patients is of particular interest because they have been largely overlooked in earlier studies. They represent an older population with long-standing DM where hypoglycemia unawareness is often recurrent and incapacitating. In addition, long-standing DM makes optimal glycemic control mandatory to prevent microvascular complications.

Methods

In this retrospective review study,, we examined available data in patients with T1DM at the Malcom Randall VA Medical Center diabetes clinic in Gainesville, Florida, between March and December of 2018 who agreed to use AIP. In this clinic, the AIP system was offered to T1DM patients when the 4-year warranty of a previous insulin pump expired, they had frequent hypoglycemic events, or they were on multiple daily injections and were proficient with carbohydrate counting and adjusting insulin doses and willing to use an insulin pump. Veterans were trained on AIP use by a certified diabetes educator and pump trainer in sessions that lasted 2 to 4 hours depending on previous experience with AIP. Institutional review board approval was obtained at the University of Florida.

Demographic and clinical data before and after the initiation of AIP were collected, including standard insulin pump/CGM information for the Medtronic 670G and Guardian 3 Sensor AIPs. Several variables were evaluated, including age, gender, year of DM diagnosis, time of initiation of AIP, HbA1c, download data (percentage sensor wear, time in automated mode and manual mode, time in/above/below range, bolus information, insulin use, average sensor blood glucose, average meter blood glucose, pump settings), weight, body mass index (BMI), glucose meter information, history of hypoglycemia unawareness.

The primary outcome for this study was safety as assessed by percentage of time below target range on glucose sensor (time below target range is defined as < 70 mg/dL). We also addressed the secondary endpoint of efficacy as the percentage of time in-range defined as blood glucose per glucose sensor of 70 mg/dL to 180 mg/dL (efficacy), percentage of glucose sensor wear, and HbA1c.

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