Plasma disappearance and distribution volume of polyfructosan in type 1 (insulin-dependent) diabetes mellitus

The simultaneous plasma disappearance curves of the extracellular marker polyfructosan and 125I-fibrinogen were recorded for 3 h in 24 male long-term diabetic patients. Eight normal subjects served as a control group. The patients were divided into three groups according to their urinary albumin excretion: Group 1 had normal albumin excretion (< 30 mg/24 h), Group 2 had microalbuminuria (30-300 mg/24 h), and Group 3 had clinical nephropathy (> 300 mg/24 h). Using fibrinogen as a plasma volume reference, the permeability surface product (PdS), the plasma clearance rate at 10 min C1(10), and the extracellular volume (ECV) were determined from the polyfructosan curves. Plasma volume was similar in all groups, and no differences were found between Group 1 and the control group. PdS was higher in the albuminuric groups, but barely to reach significant levels (p = 0.08-0.03), while C1(10) was significantly elevated (p < 0.01). The ECV was also significantly higher in these patients (p = 0.02-0.005), resulting in a marked decrease of the plasma volume to extravascular volume ratio. The results suggest a general degeneration of perivascular resistance components in diabetic microvascular complications, followed by secondary alterations of fluid balance, due to decreasing colloid osmotic counterpressure and eventually increasing transcapillary hydrostatic pressure.