Quantitative sweat test in diabetics with neuropathic foot lesions.

The volume of sweat produced by axon reflex stimulation using acetylcholine was measured in one foot each of 35 control subjects and 52 feet of 37 diabetic patients (28 with neuropathic ulceration, 11 with Charcot arthropathy, nine with somatic neuropathy but no foot lesion and four with no evidence of somatic neuropathy). In controls, the volume of sweat was greater in males than females. A flare response was seen in 94% of control feet. In diabetics, the volume of sweat was within the control range in 17 feet, increased in one, reduced in seven, and absent in 27. Sweating was absent in 75% of feet with a neuropathic ulcer; a flare response was absent in 86% of them. Sweating was only absent in 36% of feet with Charcot arthropathy and was increased in one, whereas the flare response was absent in all. Autonomic cardiovascular reflexes were more frequently abnormal than the sweat test; sweating was absent in only one patient with normal cardiovascular reflexes.