Skin temperature in the neuropathic diabetic foot

Several authors have reported higher skin temperature in the feet of diabetic subjects with autonomic neuropathy. We reexamined this association in a cross-sectional study of 712 veterans with diabetes mellitus. Potential subjects included all diabetic patients enrolled in a general internal medicine clinic at a veterans affairs healthcare system. Sensory neuropathy was defined as any pedal insensitivity to the 5.07 monofilament. Autonomic neuropathy was determined using standard cardiovascular reflex tests. An infrared surface scanner was used to measure foot skin temperature at multiple sites. Subjects with sensory neuropathy had lower mean plantar foot skill temperature than those without (28.4 degreesC vs. 28.9 degreesC, P=.0101). Autonomic neuropathy as a dichotomous variable was unrelated to foot skill temperature. Foot skill temperature, though, negatively correlated with greater drop in systolic blood pressure with standing, which is an indicator of autonomic neuropathy (r=-.08, P=.0385). Adjustment for potential confounding factors using multiple linear regression analysis resulted in diminution of the associations between foot skin temperature and sensory neuropathy or orthostatic blood pressure drop, but the latter association remained statistically significant in the right foot. Diabetic veterans with sensory or autonomic neuropathy do not have higher foot skin temperature. Our results suggest that skin temperature may be slightly lower with higher orthostatic blood pressure fall. Other causes exist for the frequently observed differences in skill temperature in the feet of diabetic subjects. (C) 2001 Elsevier Science Inc. All rights reserved.