Cutaneous microcirculation of diabetic foot: combined isolated cold stress testing and laser Doppler flowmetry study

We evaluated the peripheral microvascular response to an isolated cold stress test in patients with diabetes of various severities. We studied four groups: diabetics without neuropathy (group A: six patients), diabetics with peripheral motosensory neuropathy (group B: 12 patients), diabetics with peripheral vascular disease (group C: eight patients), and healthy controls (group D: 16 patients). Digital temperatures of all four groups decreased during the 20-minute cooling period, though more in the controls, then increased during the 20-minute rewarming period with no difference among the groups. The digital temperatures of diabetics with and without neuropathy were higher than those of diabetics with peripheral vascular disease and controls throughout. Higher mean digital skin temperature was also noted in groups A and B throughout. Significant decreases in laser Doppler flowmetry value from the last minute of acclimatization to the last minute of the cooling session were found in groups A, B, and D. A significant increase during rewarming was found only in group A (p = 0.0475). Our study showed that increased digital vascular flow was consistent with arteriovenous shunting and abnormal vascular control in diabetics with and without neuropathy. Diabetic patients with peripheral vascular disease had the lowest value and the least fluctuation in laser Doppler flowmetry, but their digital skin temperature did not differ significantly from that of the normal subjects.