Vibration thresholds are increased at low frequencies in the sole of the foot in diabetes-a novel multi-frequency approach.

AIMS

To evaluate multi-frequency tactilometry as a method to measure vibrotactile sense in the sole of the foot in subjects with diabetes.

METHODS

Vibration thresholds were investigated at five frequencies (8, 16, 32, 64 and 125 Hz) at three sites (first and fifth metatarsal heads and heel) in the sole of the foot in subjects with Type 1 and Type 2 diabetes (n = 37). Thresholds were compared with healthy, age- and gender-matched subjects (n = 37) and related to glycaemic levels, subjective estimation of sensation in the feet and to perception of touch.

RESULTS

Vibration thresholds were significantly higher in subjects with diabetes compared with healthy subjects at low frequencies (8, 16 and 32 Hz) at all measured sites, and also at 64 Hz for the metatarsal heads. Perception of touch and subjective estimation of sensation were significantly impaired in subjects with diabetes. Glycaemic levels, which were higher in subjects with diabetes, did not correlate with vibration thresholds at 32 Hz (most sensitive to Meissner's corpuscles) or with touch thresholds in subjects with diabetes. Vibration thresholds at 32 Hz correlated significantly with perception of touch (rho = 0.45-0.65; P < 0.01) and with subjective sensation (rho = -0.38 to -0.52; P < 0.001) in subjects with diabetes. Perception of touch and subjective estimation of sensation did also correlate (rho = -0.51 to -0.80; P < 0.002).

CONCLUSIONS

Tactilometry is effective in detecting neuropathy in the sole of the foot at low frequencies of mainly 8-32 Hz, indicating that at least Meissner's corpuscles, or their related large nerve fibres, are affected by diabetes.