Skin blood cell flux in insulin‐dependent diabetic subjects in relation to retinopathy or incipient nephropathy

We studied the relationship of retinal and/or renal microvascular complications and duration of disease with altered finger skin microcirculation in insulin-dependent diabetic (IDDM) subjects. Short-term and long-term IDDM subjects without complications or with proliferative retinopathy or incipient nephropathy were investigated with laser-Doppler fluxmetry. An increased resting flux in skin microcirculation was found in short-term (median: 34 perfusion units, PU) and uncomplicated long-term IDDM subjects (25 PU) as compared with age-matched healthy controls (18 PU), which suggests a generalized dilatation of the microcirculation throughout the body. In long-term IDDM subjects with retinopathy we also observed an increased resting flux (37 PU), but in subjects with incipient nephropathy resting flux was decreased (17 PU) relative to the other diabetic subjects, to a level not different from the healthy control group. Post-occlusive hyperaemic peak flux was decreased in patients with incipient nephropathy relative to the other diabetic patients, which suggests a defect in maximal arteriolar vasodilatation. No differences were found between the groups in the venoarteriolar reflex during venous occlusion. In conclusion, IDDM patients demonstrated increased red blood cell flux. However, with the occurrence of incipient nephropathy the resting flux and the maximal post-occlusive vasodilatation decreased, which suggests that development of nephropathic changes in diabetes is representative of a more generalized alternation of microvascular flow regulation. Local neurogenic microvascular control appears to be unaffected in these patients.