This is a single-centre, randomised, double-blind, three-period, complete cross-over trial comparing the pharmacokinetic and the pharmacodynamic properties of BioChaperone® insulin lispro and the two active comparators Fiasp® and Novorapid® when given as a bolus on top of basal delivery with an insulin pump in subjects with type 1 diabetes mellitus. Each subject will be randomly assigned to a treatment sequence consisting of 3 dosing visits during which the subject will receive the investigational products. In a euglycaemic clamp setting, subjects will be given a bolus dose of 0.15 U/kg body weight.