Transcutaneous oxygen, laser Doppler flowmetry, peroneal nerve motor conduction velocity and skin temperature were assessed in both legs of 34 diabetic patients, who had a mean age of 41 (range 29-77) years, and diabetes duration of 21 (3-34) years. Transcutaneous oxygen significantly correlated with peroneal nerve motor conduction velocity (r = 0.59 p < 0.001) and laser Doppler flowmetry (r = 0.7 p < 0.001). Laser Doppler flowmetry correlated weakly with peroneal motor conduction velocity, (r = 0.34 p < 0.05). In each patient the leg with the higher transcutaneous oxygen (mean 70.2 +/- 9.3 (SD) mmHg) had a significantly higher peroneal motor conduction velocity (45.3 +/- 7.1 vs 41.5 +/- 6.3 m/s, p < 0.01), than the leg with the lower transcutaneous oxygen (61.0 +/- 11.9 mmHg), though no difference in skin temperature was observed, 31.4 +/- 0.4 vs 31.1 +/- 0.5 degrees C. We then assessed the potential for reversibility of conduction velocity deficits in ten non-diabetic patients, aged 59 (52-77) years, undergoing unilateral femoro-popliteal bypass, measuring transcutaneous oxygen, peroneal nerve motor conduction velocity and skin temperature pre- and 6 weeks post-surgery. In the control leg (unoperated) there was no significant change in transcutaneous oxygen (63.2 +/- 8.8 vs 63.0 +/- 4.6 mm Hg), peroneal nerve motor conduction velocity (45.1 +/- 7.8 vs 43.4 +/- 7.2 m/s) or skin temperature (30.8 +/- 1.3 vs 30.2 +/- 1.2 degrees C) after surgery (all NS).(ABSTRACT TRUNCATED AT 250 WORDS)