Motor neuropathy.

In distal symmetric sensorimotor polyneuropathy (DSPN) in diabetes, involvement of the motor system is rarely seen. Using dynamometry, substantial weakness at the ankle and knee has been found in type 1 and type 2 diabetic patients. The muscle weakness is found only in diabetic patients with DSPN, and is closely related to signs and severity of DSPN. In long-term follow-up studies, neuropathic patients have accelerated loss of muscle strength. Studies using MRI have shown that muscle weakness is paralleled by muscular atrophy within the feet and lower legs and in follow-up studies this atrophy is accelerated compared to healthy controls and non-neuropathic patients. In large-scale studies of diabetic subjects, lower muscle quality has been found, which indicates that even with preserved muscle strength diabetes per se causes lower strength per unit striated muscle. Muscle weakness causes slower movements of the feet and legs, unstable gait, and more frequent falls. Furthermore, weakness is also an independent risk factor for the development of foot ulcers. Training may improve strength, postural stability, and walking performance; however, this still needs to be studied including patients with various degrees of DSPN.