Neuropathy is a frequent complication in diabetes and most commonly seen as distal symmetrical sensorimotor polyneuropathy (PN). Involvement of the motor system is infrequently seen at the clinical examination. However, with the application of quantitative techniques, that is, isokinetic dynamometry, type 1 and type 2 diabetic patients have been detected to have weakness at the ankle and the knee. Muscle weakness is found only in diabetic patients with PN, while non-neuropathic patients even with long-term diabetes have normal strength. The weakness is closely related to signs and severity of PN. With the use of magnetic resonance imaging, muscle weakness is found to be paralleled by muscular atrophy, which is observed in the feet and at the lower leg. Following diabetic patients for 8–10 years, we have observed accelerated loss of muscle strength in patients with symptomatic PN; similarly, accelerated loss of muscle mass is observed in the feet and lower legs. In large-scale studies of diabetic and non-diabetic subjects, lower muscle quality in diabetic patients is also found. Thus, in addition to PN, diabetes per se leads to lower strength per unit striated muscle. Muscle weakness is related to the slowing of movements, unstable gait, and more frequent falls. Furthermore, motor dysfunction leads to an increased risk of developing a foot ulcer due to due to alterations of the biomechanics of the feet caused by muscle atrophy. This may lead to an increased skin pressure that may lead to foot ulceration and ultimately amputation. Muscle and balance training may improve strength, postural stability, and walking performance; however, this needs to be studied in more detail. Copyright © 2012 John Wiley & Sons, Ltd.