Diabetic vascular lesions and peripheral autonomic neuropathy are both closely linked to long-term metabolic control of diabetes. Transcutaneous oxygen tension (P(tc)O2) measurements were made to elucidate whether autonomic neuropathy disturbs the cutaneous microcirculatory blood flow, and whether long-term glucose normalization ameliorates such impairment. Twenty-eight type 1 (insulin-dependent) diabetic patients in whom clinically significant macroangiopathy had been excluded by angiography were studied, subdivided into group A (n = 14; before simultaneous pancreas/kidney transplantation (SPKT); mean age 35 years, range 22-51 years; mean duration of diabetes 24 years, (range 15-32) years and group B (n = 14; mean 31 months, range 2-101 months, after successful SPKT; mean age 35 years, range 19-56 years; mean duration of diabetes 22 years, range 14-29 years). On addition there was a group (group C) of age- and sex-matched healthy control subjects (n = 14; mean age 35 years, range 23-62 years). P(tc)O2 measurements included basal recordings at 44-degrees-C on the leg and the foot, functional recordings at 44-degrees-C after arterial occlusion of the limb for 4 min, measurements during breathing 51 oxygen per minute and finally while standing up (stand up dP50/dt). All subjects underwent extensive cardiac autonomic testing. In this cross-sectional study the recordings of basal values and of the functional parameters after arterial occlusion and during breathing oxygen did not differ significantly between groups A, B and C. The stand-up dP50/dt values were not significantly different between groups A and B (0.43 +/- 0.02 vs 0.47 +/- 0.03 mmHg/s, mean + SEM); but A + B values were significantly higher than in C (0.22 +/- 0.01 mmHg/s; P<0.001). These values were correlated significantly with all parameters of cardiac autonomic neuropathy (r range-0.56 to -0.88; P<0.001). It may be concluded that normalization of blood glucose by pancreatic transplantation is not able to ameliorate peripheral microcirculation, but that measurement of transcutaneous oxygen tension is a possible new technique for quantifying alterations in the venoarteriolar reflex in peripheral diabetic autonomic neuropathy that lead to disturbed peripheral microcirculation in diabetic patients.