A report is presented on InGaN/GaN multiple quantum well laser diodes, grown by metal organic vapour phase epitaxy on c-plane sapphire substrates, including an Al0.83In0.17N cladding layer lattice-matched to GaN. Lasing action is demonstrated for gain-guided devices at room temperature under pulsed current injection conditions. Direct comparison with structures including only a standard Al0.07Ga0.93N bottom cladding shows an improved optical confinement. This is exemplified by a decreased threshold current density.