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Closed-loop insulin delivery has glycemic benefits during sleep at the expense of sleep quality

Compared to sensor pump therapy, closed-loop insulin delivery increased glucose time in range and reduced hypoglycemic episodes, but impaired sleep quality.

Compared to sensor-pump therapy, first-generation closed-loop therapy has glycemic benefits during sleep for older people with type 1 diabetes (T1D), but deteriorates some measures of sleep quality, according to a study published in Diabetes technology and therapy.

First-generation closed-loop systems incorporate continuous glucose monitoring communicating with an insulin pump and automated glucose-responsive basal insulin dosing. The glycemic benefits of closed-loop therapy are greatest overnight, when food intake and physical activity have less of an impact on insulin requirements.

Although advances in diabetes technology have the potential to improve both blood sugar levels and sleep quality, the technology may also reduce sleep quality due to system alarms, patient intervention requirements user and physical discomfort associated with the device.

Researchers conducted a randomized trial to report the glycemic impact of closed-loop therapy during sleep measured objectively. They compared sleep glucose outcomes and sleep quality of closed-loop therapy with sensor-pump therapy in older people with T1D.

In the Older Adult Closed-Loop Randomized Crossover (ORACL) trial of first-generation closed-loop therapy (MiniMed 670G), participants wore noninvasive actigraphy and completed sleep diaries for 14-day periods. Participants were aged 60 or older, had T1D for 10 years or more, and used an insulin pump.

A total of 30 elderly people participated with an average age of 68 years and an average duration of T1D of 38 years.

At baseline, 14 participants (47%) reported inadequate sleep quality. 3 other participants reported using pharmacological therapy to facilitate sleep, and 3 were taking antidepressants that may affect sleep.

None reported taking stimulant medication.

During sleep measured objectively with closed-loop therapy versus a sensor pump, glucose time in the range of 70 to 180 mg/dL (3.9 to 10.0 mmol/L) was higher (90 .3% versus 78.7%, respectively, difference, 8.2 percentage points, 95% CI, 1.5-13.0; P = 0.008).

Additionally, time spent in a narrow blood glucose range of 70–140 mg/dL (3.9–7.8 mmol/L) during sleep was longer with closed-loop therapy (difference, 12.8 points percentage, 95% CI, 6.0 to 19.5; P

There were also fewer hypoglycemic episodes per sensor (18 versus 43, respectively; incident rate ratio, 0.40; 95% CI, 0.20-0.55; P = 0.007).

The favorable between-treatment effects of closed-loop improving time in the interval were generally observed from the fourth hour of sleep. For both therapies, almost all times below range occurred within 5 hours of sleep onset. More time below range was observed with sensor-augmented therapy during this period.

Average sleep efficiency was high overall, although lower with closed-loop therapy compared to sensor pump therapy (82% vs. 85%, respectively; difference, -2.9 percentage points 95% CI -5.0 to -0.8; P= 0.009).

Sleep quality recorded in daily sleep diaries was worse with closed-loop therapy (P= 0.006). The Pittsburgh Sleep Quality Index did not differ.

System alarms were felt during most nights of sleep with both treatments.

During monitored sleep with closed-loop therapy, there were 30% more system alarms (P P

“This benefit is clinically important because hypoglycemia-related situations typically require intervention for therapy and/or insulin pump adjustment before resuming sleep,” the authors wrote.

No episodes of severe hypoglycaemia or other significant adverse effects during sleep occurred throughout the 8-month trial.

Overall, the results suggest that first-generation closed-loop therapy exhibits glycemic benefits during sleep in older adults, with deterioration in some measures of sleep quality. The findings build on previous evidence that closed-loop therapy reduces hypoglycemia overnight. Simultaneously, they highlight the potential burden of using the closed-loop system on sleep quality.

The authors suggest that although sleep quality did not improve with first-generation closed-loop therapy, it is clinically reassuring that sleep quality did not deteriorate markedly. While total sleep time and sleep efficiency were slightly lower with the closed loop, participants met recommendations for minimum sleep duration per night.

The authors encourage prioritizing sleep quality when advancing closed-loop technology. “As closed-loop technologies improve in the future, with advanced glucose sensors and increasingly automated algorithms, less sleep disruption from system alarms is expected,” they wrote.

“Future developments in diabetes technology, including more automated closed-loop algorithms and improved glucose sensor technology, have the potential to further improve sleep glucose levels and sleep quality in people with diabetes. type 1,” they concluded.


Chakrabarti A, Trawley S, Kubilay E, et al. Effects of closed-loop insulin delivery on sleep glucose levels and sleep quality in older adults with type 1 diabetes: results from the ORACL trial. Published online July 4, 2022. Diabetes Technol Ther.doi:10.1089/dia.2022.0110