The aim of this study was to assess whether the dual-hormone (insulin and glucagon) artificial pancreas reduces hypoglycaemia compared with the single-hormone (insulin alone) artificial pancreas during two types of exercise. An open-label randomised crossover study comparing both systems in 17 adults with type 1 diabetes (age, 37.2 ± 13.6 years; HbA1c, 8.0 ± 1.0% [63.9 ± 10.2 mmol/mol]) during two exercise types on an ergocycle and matched for energy expenditure: continuous (60% $$ \overset{.}{V}{\mathrm{O}}_{2\mathrm{peak}} $$ for 60 min) and interval (2 min alternating periods at 85% and 50% $$ \overset{.}{V}{\mathrm{O}}_{2\mathrm{peak}} $$ for 40 min, with two 10 min periods at 45% $$ \overset{.}{V}{\mathrm{O}}_{2\mathrm{peak}} $$ at the start and end of the session). Blocked randomisation (size of four) with a 1:1:1:1 allocation ratio was computer generated. The artificial pancreas was applied from 15:30 hours until 19:30 hours; exercise was started at 18:00 hours and announced 20 min earlier to the systems. The study was conducted at the Institut de recherches cliniques de Montreal. During single-hormone control compared with dual-hormone control, exercise-induced hypoglycaemia (plasma glucose