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Artificial pancreas improves time in range vs. insulin pump therapy
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Children and adults with type 1 diabetes assigned to an artificial pancreas for 6 months spent an average of 2.6 fewer hours per day in hyperglycemia and 13 fewer minutes per day in hypoglycemia when compared with participants using sensor-augmented insulin pump therapy, according to findings published in The New England Journal of Medicine.
In reporting findings from the randomized controlled trial, which included participants aged 14 to 71 years initially using either insulin pump or multiple daily injection therapy, the researchers noted that the beneficial effects associated with the closed-loop insulin delivery system were observed during daytime and nighttime and were particularly prominent in the second half of the night.
“What is so exciting about this study is that, compared with other closed-loop insulin delivery systems, we have 11% increased time in range, which is a least 2.6 hours per day, the frequency of hypoglycemia and hyperglycemia were reduced in all study subjects and the benefits were achieved in the first month of the study and consistently sustained throughout the 6 months of the trial,” Carol Levy, MD, clinical director of the Mount Sinai Diabetes Center, told Endocrine Today. “The rate of use was 92% throughout the trial, which is huge. We really see durability of use and benefit. It was an incredibly exciting trial to be a part of for those reasons.”
Study design
In a parallel-group, unblinded, randomized controlled trial, Levy and colleagues analyzed data from 168 adolescents and adults aged at least 14 years with type 1 diabetes treated with insulin pump (79%) or multiple daily injection therapy (21%), recruited from seven university centers in the United States (50% female; mean age, 33 years). There was no study restriction on baseline HbA1c level, which ranged from 5.4% to 10.6%. The trial consisted of a 2- to 8-week run-in phase, dependent upon whether participants were pump or continuous glucose monitor naive, followed by random assignment to a closed-loop system (n = 112; t:slim X2 insulin pump with Control-IQ technology, Tandem Diabetes Care, with Dexcom G6 CGM) or sensor-augmented pump therapy (controls; n = 56) for 26 weeks. In-person follow-up visits took place at 2, 6, 13 and 26 weeks; telephone check-ins took place at 1, 4, 9, 17 and 21 weeks, with data from devices downloaded and reviewed during each visit and telephone contact. The primary outcome was percentage of time spent in the recommended glucose range of 70 mg/dL to 180 mg/dL and secondary outcomes were time spent in hyperglycemia and hypoglycemia and HbA1c at 26 weeks.
‘Improved glucose control’
Between baseline and 6 months, mean percentage of time in range increased from 61% to 71% for the closed-loop group and remained unchanged at 59% for controls, for a mean difference of 11 percentage points (95% CI, 9-14). Mean difference for percentage of time spent in hypoglycemia was –0.88 percentage points (95% CI, –1.19 to –0.57), favoring the closed-loop system. Mean difference in HbA1c at 26 weeks was –0.33 percentage points (95% CI, –0.53 to –0.13), again favoring the closed-loop group. Participants in the artificial pancreas group spent an average of 90% of the time in closed-loop mode during the 6-month trial, according to researchers. There were no serious hypoglycemic events. One participant in the closed-loop group experienced diabetic ketoacidosis.
“The study demonstrated improved glucose control, both day and night, across a wide range of ages with a variety of glucose control,” Levy said. “People did not need to be familiar with diabetes technology, as we started people who were glucose sensor naive and insulin pump naive. We went for a very broad range of patients. Additionally, no patient dropped out from this trial, which says a lot about the patients’ commitment and how much they felt the benefits of this system.”
The researchers noted that insulin pumps used by controls did not have a feature to suspend insulin for predicted hypoglycemia, known as “suspend-before-low,” which is now available for some pumps and has been shown to reduce the amount of CGM-measured hypoglycemia.
– by Regina Schaffer
Disclosures: Tandem Diabetes Care reviewed the manuscript but was not involved in trial design, conduct, data analysis or manuscript preparation. Levy reports she has received grants from Abbott Diabetes, Dexcom, the Helmsley Foundation, JDRF and Lexicon. Please see the study for all other authors’ relevant financial disclosures.
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Brown SA, et al. N Engl J Med. 2019;doi:10.1056/NEJMoa1907863.
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