Autonomic neuropathy and transcutaneous oxymetry in diabetic lower extremities

Summary Transcutaneous oxygen tension is a useful method with which to assess the functional status of skin blood flow. The reduced values observed in diabetic patients have been interpreted as a consequence of peripheral vascular disease. However, diabetic patients show lower transcutaneous oxygen tension values than control subjects with equivalent degrees of peripheral vascular disease, suggesting that additional factors are involved. Since the autonomic nervous system influences peripheral circulation, we studied the relationship between autonomic neuropathy and foot transcutaneous oxymetry in non-insulin-dependent diabetic (NIDDM) patients without peripheral vascular disease. The following age-matched patients were selected and evaluated: control subjects, C, (n=20), NIDDM patients without autonomic neuropathy, D, (n=16) and with autonomic neuropathy, DN, (n=20). All diabetic patients showed lower transcutaneous oxygen tension values than control subjects, while no differences were observed between the diabetic patients with and without autonomic neuropathy. In addition the saturation index that increases in the presence of autonomic neuropathy does not correlate with foot TcPO₂. In conclusion autonomic neuropathy does not influence foot TcPO₂ and therefore it is unlikely that it contributes to development of foot lesions during induction of foot skin ischaemia.Abbreviations NIDDM Non-insulin-dependent diabetes mellitus - TcPO₂ transcutaneous oxymetry - A-V arterio-venous shunts - PVD peripheral vascular disease - HbA_1c glycated haemoglobin - SI saturation index