Closed-loop glucose control in young people with type 1 diabetes during and after unannounced physical activity: a randomised controlled crossover trial

Abstract

Aims/hypothesis: Hypoglycaemia during and after exercise remains a challenge. The present study evaluated the safety and efficacy of closed-loop insulin delivery during unannounced (to the closed-loop algorithm) afternoon physical activity and during the following night in young people with type 1 diabetes.

Methods: A randomised, two-arm, open-label, in-hospital, crossover clinical trial was performed at a single site in Slovenia. The order was randomly determined using an automated web-based programme with randomly permuted blocks of four. Allocation assignment was not masked. Children and adolescents with type 1 diabetes who were experienced insulin pump users were eligible for the trial. During four separate in-hospital visits, the participants performed two unannounced exercise protocols: moderate intensity (55% of [Formula: see text]) and moderate intensity with integrated high-intensity sprints (55/80% of [Formula: see text]), using the same study device either for closed-loop or open-loop insulin delivery. We investigated glycaemic control during the exercise period and the following night. The closed-loop insulin delivery was applied from 15:00 h on the day of the exercise to 13:00 h on the following day.

Results: Between 20 January and 16 June 2016, 20 eligible participants (9 female, mean age 14.2 ± 2.0 years, HbA_1c 7.7 ± 0.6% [60.0 ± 6.6 mmol/mol]) were included in the trial and performed all trial-mandated activities. The median proportion of time spent in hypoglycaemia below 3.3 mmol/l was 0.00% for both treatment modalities (p = 0.7910). Use of the closed-loop insulin delivery system increased the proportion of time spent within the target glucose range of 3.9-10 mmol/l when compared with open-loop delivery: 84.1% (interquartile range 70.0-85.5) vs 68.7% (59.0-77.7), respectively (p = 0.0057), over the entire study period. This was achieved with significantly less insulin delivered via the closed-loop (p = 0.0123).

Conclusions/interpretation: Closed-loop insulin delivery was safe both during and after unannounced exercise protocols in the in-hospital environment, maintaining glucose values mostly within the target range without an increased risk of hypoglycaemia.

Trial registration: Clinicaltrials.gov NCT02657083 FUNDING: University Medical Centre Ljubljana, Slovenian National Research Agency, and ISPAD Research Fellowship.

Keywords: Clinical science; Devices; Diabetes in childhood; Exercise; Hypoglycaemia.

Fig. 1

Study flow diagram. Schedule for all sessions was the same: 13:00 h, lunch; 16:00 h, snack; 16:30–19:30 h, exercise time; 19:45 h, dinner; next day 8:00 h, breakfast; 13:00, lunch

Fig. 2

Median (IQR) sensor glucose during closed-loop (blue) and open-loop (red) insulin delivery, from exercise period (17:00 h) until morning (07:00 h), with standard glucose outcome measures [22] and common glucose target value of 6.1 mmol/l

Fig. 3

Median (IQR) sensor glucose during closed-loop (blue, a, b) and open-loop (red, c, d) insulin delivery, from exercise period (17:00 h) until morning (07:00 h), for 55% $\stackrel{\cdot }{V}{\mathrm{O}}_{2max}$ moderate physical activity protocol (a, c) and 55/80% $\stackrel{\cdot }{V}{\mathrm{O}}_{2max}$ moderate physical activity with high-intensity sprints (b, d) with consensus glucose outcome measures [22] and mean glucose target value 6.1 mmol/l