<b>Objective: </b>To assess the efficacy and
feasibility of a dual-hormone closed loop system with insulin and a novel
liquid stable glucagon formulation compared with an insulin-only closed loop
system and a predictive low glucose suspend system.
<p><b>Research Design and
Methods:</b> In a 76-hour,
randomized, crossover, outpatient study, 23 participants with type 1 diabetes
used three modes of the Oregon Artificial Pancreas system: (1) dual-hormone (DH)
closed loop control, (2) insulin-only single-hormone (SH) closed loop control and
(3) predictive low glucose suspend (PLGS). The primary endpoint was
percent time in hypoglycemia (<70 mg/dL) from start of in-clinic aerobic exercise
(45mins at 60% VO<sub>2max</sub>) to 4 hours after.</p>
<p><b>Results:</b> DH reduced hypoglycemia compared with SH
during and after exercise (DH 0.0% [0.0-4.2], SH 8.3% [0.0-12.5], p=0.025).
There was an increased time in hyperglycemia (>180mg/dL) during and after exercise
for DH vs SH (20.8% DH vs. 6.3% SH, p=0.038). Mean glucose during the entire
study duration was: DH 159.2, SH 151.6, PLGS 163.6 mg/dL. Across the entire
study duration, DH resulted in 7.5% more time in target range (70-180 mg/dL)
compared with the PLGS system (71.0% vs. 63.4%, p=0.044). For the entire study
duration, DH had 28.2% time in hyperglycemia versus 25.1% for SH (p=0.044) and
34.7% for PLGS (p=0.140). Four participants experienced nausea related to
glucagon leading 3 to withdraw from the study. </p>
<p><b>Conclusions:</b> The glucagon formulation demonstrated
feasibility in a closed loop
system. The dual-hormone system reduced hypoglycemia during and after
exercise with some increase in
hyperglycemia.</p>