Influence of diabetic neuropathy on skin microcirculation assessed by transcutaneous oxymetry

Skin microcirculation was investigated in 45 patients with long term diabetes and with severe, moderate or no neuropathy, and in 15 controls. Transcutaneous oxygen pressure (tcPO2) measurements on the forefoot were performed at 37 degrees C to assess local capillary flow at rest, during leg dependency and reactive hyperaemia, and also at 44 degrees C, including the response to oxygen inhalation. TcPO2 (37 degrees C) at rest was significantly elevated with an increasing degree of neuropathy (Controls: 4.8 +/- 3.7; patients without neuropathy: 4.2 +/- 2.9; with moderate neuropathy: 6.0 +/- 2.9 (p < 0.01); with severe neuropathy: 7.2 +/- 4.2 mmHg (p < 0.001)). Leg dependency resulted in a decrease of tcPO2 in the controls, while an increase was observed in 18.6% of the measurements in patients, reflecting a disturbed vasoconstrictor response. Regardless of neuropathy, absolute tcPO2 values during reactive hyperaemia were reduced in all patient groups as well as tcPO2 (44 degrees C) and its increase during oxygen breathing. Diabetic neuropathy is likely to increase local capillary flow, while the other differences to healthy controls may be contributed to a microcirculation disorder independent of neuropathy.