Cold and warm cutaneous sensation in diabetic patients

The assessment of cutaneous thresholds for thermal sensation is now recognized as a valuable method to detect small nerve fibre function in diabetes. Methods commonly used do not allow separate measurements of warm and cold perception. However, there is evidence that the fibre subtypes which signal cold and warm sensation are different (A-delta-fibres and C-fibres, respectively). To investigate if diabetes affects cold and warm sensation equally, thresholds were assessed separately in 30 diabetic patients (age 47.9 +/- 15.1 (+/- SD) years; duration of diabetes, 19.1 +/- 13.3 years). Comparisons were made with 71 non-diabetic control subjects (age 59.7 +/- 22.1 years). Thermal discrimination thresholds for cold and warm sensation were determined for the left foot with a two-alternative forced choice method. In both diabetic patients and in the control group cooling thresholds were smaller than warming thresholds. In diabetic patients log thermal discrimination thresholds for warmth increased 0.1 per decade (p less than 0.001), a relationship comparable to that seen in non-diabetic patients. There was no relationship between cooling thresholds and age in diabetic patients despite a significant (p less than 0.001) deterioration with age in control subjects. This difference in the influence of age on cold sensitivity was significant (p less than 0.03). Both warm and cold sensation were not related to the duration of diabetes. We conclude that assessment of warm threshold is preferred for the detection of minor disturbances of small nerve fibre function in diabetes.