Improvements in diabetic microangiopathy after successful simultaneous pancreas-kidney transplantation: a computer-assisted intravital microscopy study on the conjunctival microcirculation.

A computer-assisted intravital microscopy technology has been developed to noninvasively and objectively study diabetic microangiopathy in the conjunctival microcirculation of type-1 diabetics. Quantitative characterization of the conjunctival microcirculation was performed on 12 patients pre- and 18 months postsimultaneous pancreas-kidney transplantation (SPK). Healthy nondiabetic volunteers (n=12), solitary kidney (K) transplanted type-1 diabetics (n=5), and nontransplanted type-1 diabetics (n=12) served as controls. Pre-SPK diabetics showed abnormal-sized venules (diameter=66+/-7 microm) and reduced presence of arterioles (arteriole length/area=18+/-6 microm(-1)) compared with nondiabetic controls (53+/-4 microm; 31+/-8 microm(-1); P<0.05). The computed vascular perfusion capacity of the conjunctival microvasculature was diminished in the same patients (pre-SPK diabetics=49+/-9%; nondiabetic healthy controls=71+/-6%; P<0.05). Significant improvement in microangiopathy was observed in all post-SPK diabetics (diameter=58+/-6 microm; arteriole length/area=26+/-9 microm(-1); vascular perfusion=63+/-8%; P<0.05) 18 months post-SPK. Blood flow velocities in the conjunctival microcirculation in the same post-SPK patients showed noticeable but not significant improvements (nondiabetic controls=2.94+/-0.57 mm/sec; pre-SPK=1.23+/-0.49 mm/sec; post-SPK=1.65+/-0.42 mm/sec). The solitary kidney transplant controls (post-K) showed no significant improvements in diabetic microangiopathy, confirming the unique role of the pancreas in SPK. In general, significant improvements (P<0.05) in diabetic microangiopathy were observed in all 12 diabetics 18 months post-SPK but not in the controls.