Skin microvascular autoregulatory responses in type I diabetes: the influence of duration and control.

We have studied skin microvascular autoregulatory responses in healthy control subjects (n = 11) and three subgroups of uncomplicated Type 1 diabetics. Group 1 (n = 10) had a duration of diabetes of less than one year. Group 2 (n = 10) had a mean duration of diabetes of 11 years. Group 3 (n = 9), of similar duration to group 2, were selected on the basis of having HbAl values persistently below 9%. To assess autoregulatory capacity we determined time to peak capillary flow velocity (CBV) in single nailfold capillaries following release of 60 s arterial occlusion by videophotometric capillaroscopy, and the percentage fall in finger skin rest flow measured by laser Doppler flowmetry when 50 mm Hg venous occlusion was applied. Time to peak CBV was prolonged in groups 1 and 2 compared to controls, (controls 7.7 +/- 1.4 s, mean +/- ISD, group 1 10.7 +/- 2.9 s, p less than 0.01; group 2 11.6 +/- 3.0 s, p less than 0.002) but not in group 3 (9.3 +/- 3.0 s, NS). The percentage fall in resting microcirculatory flow in response to venous occlusion was reduced in groups 1 and 2 compared to controls (controls 57 +/- 16%, group 1 40 +/- 19%, p less than 0.05; group 2 22 +/- 16%, p less than 0.002). In group 3 the response was significantly different from the control value (group 33.7 +/- 20%, controls 57 +/- 16%, p less than 0.05). Thus skin microvascular autoregulatory responses are disturbed within the first year of diabetic life and after 10 years disease duration the impairment is more marked.(ABSTRACT TRUNCATED AT 250 WORDS)