High plantar pressure is a risk factor for diabetic foot ulcers, and it is known that restriction of ankle dorsiflexion range of motion (ROM) causes high plantar pressure. Stretching is a non-invasive and general means to improve ROM; however, the effect of stretching on the ROM and plantar pressure has not been clarified in patients with diabetes mellitus. We aimed to study the effects of intermittent weight-bearing stretching on ankle dorsiflexion ROM and plantar pressure during gait in patients with diabetes mellitus. Seven patients with diabetes mellitus participated, and their triceps surae was stretched using weight-bearing stretching with a stretch board. Five minutes of stretching was performed 4 times with a rest interval of 30 s. Ankle dorsiflexion ROM was measured with the knee flexed and extended. Peak pressure and pressure-time integral during gait were measured and calculated for the rearfoot, midfoot, forefoot, and total plantar surface before and after stretching. Ankle dorsiflexion ROM with the knee extended or bent increased significantly after stretching (P < .05). Peak pressure and the pressure-time integral decreased significantly, especially in the forefoot (P < .01), and these also decreased significantly in the total plantar surface (P < .05). The duration of foot-flat decreased after stretching (P < .05). Weight-bearing stretching improved ankle dorsiflexion ROM and reduced plantar pressure during gait. These results suggest that weight-bearing calf stretching may be an effective means to prevent and treat diabetic foot ulcers.