[Prospective Study of the Causes of Limb Numbness in Patients with Diabetes]

Many patients with diabetes mellitus (DM) experience numbness in the extremities. This DM neuropathy may be complicated by peripheral entrapment neuropathy. We prospectively investigated the cause(s) of limb numbness in DM patients.

We enrolled 23 patients with uni- or bilateral limb numbness who were treated in our DM clinic. They were 10 men and 13 women; their average age was 63 years. The average duration of their neurological symptoms was 28.3 months.

Numbness was located in the upper limb in 7 patients, the lower limb in 11, and both the upper and lower limbs in 5. Among the 12 patients with upper-limb numbness, 9 manifested carpal tunnel syndrome and one each cervical OPLL or cervical spondylosis. Of the 16 cases of lower limb numbness, 10 were attributable to tarsal tunnel syndrome, 7 to lumbar spinal disease, 3 to restless leg syndrome, 2 to piriformis syndrome, and 1 to peroneal nerve entrapment neuropathy.

In 21 of the 23 patients with uni- or bilateral limb numbness, the cause was attributable to several kinds of etiology such as entrapment neuropathy. Consequently, other treatable peripheral nerve disorders, e.g. tarsal tunnel syndrome, must be considered when diagnosing DM patients with limb numbness. Our findings suggest that therapeutic intervention to address such diseases will affect the quality of life of DM patients with limb numbness.