BACKGROUND: Increased loss of proteoglycan (PG) from glomerular basement membrane (GBM) has been postulated to alter glomerular charge selectivity which contributes to urinary loss of albumin. The glycosaminoglycan (GAG) is the degradation products of PG. Recently, one of the hypothesis suggested that urinary albumin execretion(UAE) reflects not only merely a glomerular manifes-tation but also a macrovascular disease (by Deckert et al), Wasty et al. reported a significant decrease in total GAG concentration and marked changes in their distribution in atherosclarotic plaques in human. Thus, the alterations in the metabolism of GAG might play a role in the pathogenesis of diabetic macroangiopathy. Therefore, we investigated the relationship among urinary GAG execretion rates, UAE and macrovascular disease in patients with type 2 diabetes mellitus. METHODS: We measured urinary excretion rates of GAS in type 2 diabetic patients with and without macrovascular disease ( cerebrovascular disease, ischemic heart disease and other peripheral vascular disease ) and investigated the relationships among urinary execretion of GAG, UAE and macrovascular disease in 103 patients with type 2 diabetes mellitus. RESULTS: 1) Among total 103 patients, 66 patients (64.0%) showed normoal-buminuria, 18 patients (17.5%) showed microabluminuria and 19 paitents (18.4%) showed macro albuminuria respectively. The duration of diabetes mellitus and the prevalence of hypertension, diabetic retinopathy and macrovascular disease were increased according to the degree of UAE. 2) The urinary excretion rates of GAG in type 2 diabetes mellitus with normo-, microand macro-albuminuria were 6.72+/-4.05, 9.17+/-3.26 and 14.20+/-6.13 microgram glucuronic acid/min respectively (p<0.05). The urinary GAG levels were significantly correlated with UAE (r=0.43, p<0.05). 3) The urinary excretion rates of GAG in type 2 diabetes mellitus with (n=26) and without (n=77) macrovascular disease were 6.21+/-2.75 and 9,31+/-5.59 ug glucuronic acid/min, respectively (p<0.05). CONCLUSION: 1) The urinary excretion rates of GAG were decreased in patients with macro vascular complications of type 2 diabetes mellitus. 2) The urinary excretion rates of GAG may be a possible marker of macrovascular disease in type 2 diabetes mellitus. Yet, further large prospective studies are necessary to confirm our findings.