A longitudinal evaluation of urinary glycosaminoglycan excretion in normoalbuminuric type 1 diabetic patients

Background: Previously, we found high urinary glycosaminoglycan
(GAG) concentration, together with
an altered electrophoretic pattern, in normoalbuminuric
type 1 diabetic subjects with hemoglobin A1c
(HbA1c) G8.0%. The purpose of this study was longterm
evaluation of GAG excretion variations in these
patients compared to those with HbA1c -8.0% at
baseline who maintained better metabolic control
over time.
Methods: We enrolled 26 normotensive, normoalbuminuric
type 1 diabetic patients and divided them into
two groups according to mean HbA1c levels during
the follow-up period. GAGs were isolated from 24-h
urine samples on two separate occasions, at baseline
and after a mean ("SD) follow-up of 6.8"1.1 years.
Results: All patients remained normoalbuminuric at
follow-up, and had normal urinary a1-microglobulin
levels. In patients with HbA1c -8.0%, total GAG levels
and low sulfated chondroitin sulfate-proteoglycan/
chondroitin sulfate ratio were almost unchanged during
the follow-up period. In contrast, these increased
in patients with HbA1c G8.0% and were significantly
related to both HbA1c levels and the duration of poor
glycemic control.
Conclusions: Our results show a strong influence of
hyperglycemic environment on GAG metabolism in
diabetes and indicate that the distribution pattern of
urinary GAGs, besides their total concentration, may
be predictive of altered GAG metabolism in type 1
diabetes.