Thermal tests were performed in 117 healthy subjects on the face, wrist and leg; 32 were tested on the legs with different rates of cooling and warming. Additionally 2 groups of diabetics (37 patients) were tested. Thermotesting was most sensitive on the legs using a rate of temperature change of 2.5-2.8 oC/s. Warm and cold perception should be tested separately. Cold perception testing is most sensitive. Combined tests of warm and cold thresholds as well as the testing of cool pain and heat pain do not improve results. Abnormal cold perception may be an early indicator of diabetic small fibre polyneuropathy, leading to cold trauma and ulcers on the feet.