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.