[Urinary glycosaminoglycans in patients with incipient diabetic nephropathy]

To investigate the clinical significance of the urinary glycosaminoglycans excretion rate (GER) in patients with incipient diabetic nephropathy. GER was measured by the dye-binding method (Whiteman, 1972) in nocturnal urines of 30 normoalbuminuric (urinary albumin albumin excretion rate (AER) < 10 micrograms/min) and 10 microalbuminuric (10 < or = AER < 200 micrograms/min) diabetics without hypertension and 24 healthy control subjects. The mean GER in microalbuminuric diabetics was 56.5 +/- 15.0 micrograms/min and was significantly higher than that in the healthy controls (41.1 +/- 12.9 micrograms/min, p < 0.01). There was no significant difference in GER between normoalbuminuric diabetics and the healthy controls (50.2 +/- 36.3 micrograms/min, p < 0.1). GER correlated positively with HbA1c levels in the diabetics (r = 0.451, p < 0.01). In diabetics with good glycemic control (HbA1c, < 8.0%), GER positively correlated with urinary transferrin and albumin excretion rates (r = 0.593, 0.584, both p < 0.01), whereas it did not correlate significantly with N-acetyl-beta-D-glucosaminidase excretion rate (NAGER). In diabetics with poor glycemic control (HbA1c > or = 8.0%), GER correlated positively with NAGER (r = 0.626, p < 0.01), whereas it did not correlate significantly with urinary transferrin and AER. These results indicate that GER may be affected by glycemic control and is associated with the severity of the glomerular basement membrane lesion in well-controlled diabetics and with the severity of the tubulointerstitial lesion in poorly controlled diabetics. The measurement of GER is useful for determining the pathophysiological state in incipient diabetic nephropathy.