Assessment of microcirculatory alterations in diabetic patients by means of capillaroscopy and laser Doppler anemometry

Background: Only minor changes of skin capillary morphology have been descr ibed in diabetic patients by means of capillaroscopy, whereas cutaneous mic rovascular dysfunction is well known. We examined correlations between func tional and morphological abnormalities of the capillaries in Type 1 and 2 d iabetic patients and the influence of diabetes duration on capillary morpho logy. Patients and Methods: Density, diameters and morphology of nailfold capilla ries were investigated in diabetic patients, 16 Type 1 and 19 Type 2, and c ompared to age- and sex-matched control groups. Capillary blood cell veloci ties (CBV) during rest: and after 3-minute arterial occlusion were measured in the dorsal middle phalangeal area of the left ring finger by means of l aser Doppler anemometry. Results: Capillary density, width and arterial limb diameter were similar i n Type 1 and 2 diabetic patients compared to their controls. Capillary diam eters of the apical part and the venous limb were enlarged in the combined analysis of Type 1 and 2 diabetic patients compared to the control group (a pex: 19.2 +/- 0.6 mum vs 17.4 +/- 0.6 mum, p = 0.0243; various limb: 17.3 /- 0.5 mum vs 15.9 +/- 0.4 mum, p = 0.0238). Tortuous capillaries were more often observed in Type 1 (n = 13 vs n = 7, p = 0.028) and 2 diabetic patie nts (n = 16 vs n = 9, p = 0.019) than in controls. In Type 1 diabetic patie nts an inverse correlation (r = -0.52; p = 0.019) was found between capilla ry density and resting CBV. In Type 2 diabetic patients capillary apex diam eter correlated positively with peak CBV (r = 0.49; p = 0.017). Disease dur ation correlated inversely with arterial limb diameter (r = -0.48; p = 0.02 0) and width of the capillaries (r = -0.48; p = 0.018) in Type 2 diabetic p atients. Conclusion: Tortuous and dilated capillaries, indicating microangiopathy, w ere Found in the skin of diabetic patients by means of capillaroscopy. Usin g laser Doppler anemometry it is possible to assess impairment of postocclu sive reactive hyperemia, due to diabetic microvascular dysfunction, in sing le capillaries. Correlations between morphological and functional microcirc ulatory alterations in diabetes may be explained by hemodynamic changes, de pending on diabetes duration.