Effect of metabolic regulation on renal leakiness to Dextran molecules in short-term insulin-dependent diabetics

Abstract

Renal clearance of dextran of two ranges of molecular size and glomerular filtration rate (GFR,⁵¹Cr-EDTA) were measured in seven short-term insulin-dependent diabetics (mean age 25 years). Measurements were carried out in the same patient during good and poor metabolic regulation (plasma glucose, mean±SEM, 6.5±0.9 and 14.8±1.5 ] mmol/l, respectively). GFR was elevated in all patients during poor metabolic regulation (119±6 ml/min/1.73 m², versus 99±2 ml/min/1.73 m² during good control, p2, and 5.2±0.3 to 6.8±0.6 ml/min/1.73 m², respectively (p< 0.05). The elevated GFR and renal dextran clearance found during poor metabolic regulation were normalized within one to three weeks of effective insulin treatment. This rapid reversibility can hardly be explained by the previously demonstrated enlargement in glomerular size and filtration surface area, since these alterations remain unchanged after more than one month of insulin treatment. The metabolic regulation did not influence the size-selective properties of the glomerular wall. Therefore, we suggest that the dominating mechanism involved in the GFR and renal dextran clearance alterations is functional, viz. increased filtration pressure.