To clarify the significance of the parameters which might indicate the abnormalities in the kidney, urinary N-acetyl-beta-D-glucosaminidase (NAG), urinary total protein (TP), urinary beta 2-microglobulin (beta 2MG) and serum NAG were determined in 61 type 1 diabetics who had neither retinopathy nor macroalbuminuria (negative albuminuria by Albustix), and in 19 age, sex-matched nondiabetic subjects. Urinary NAG, urinary TP and serum NAG levels were significantly elevated in the diabetics compared with the nondiabetic subjects, even though in the diabetics, whose duration of diabetes was not longer than 2.5 years. The relationships between these parameters and glycemic indices at different periods were studied in diabetics. Urinary NAG was correlated the strongest with the mean blood glucose level over the 7 days before the collection of urine (r = 0.47) among the 5 glycemic indices. On the other hand, urinary TP and urinary beta 2MG were correlated the strongest with the urinary glucose at the time of collection of urine (r = 0.77 and r = 0.37, respectively) among the 5 glycemic indices. No correlation of urinary NAG, urinary TP or urinary beta 2MG with stable HbA1 was observed. On the multiple regression analysis, 32% of the changes in urinary NAG, 61% of urinary TP, 19% of urinary beta 2MG and 20% of serum NAG were explained merely by the blood glucose levels, respectively. No relationship was observed among each parameter and duration of diabetes, insulin dose, urinary excretion of C-peptide or lipid levels.(ABSTRACT TRUNCATED AT 250 WORDS)