Clinical study of the tubulointerstitial change in patients with type 2 diabetes mellitus

Objective: To investigate tubulointerstitial damage in patients with type 2 diabetes mellitus (DM) by detecting urinary-N-acetyl-beta-D-glucosaminidase (NAG) levels, urinary retinol-binding protein (RBP) levels and osmolality after 13 h water-fasting. Methods: Seventy-seven patients with DM were divided into three groups according excretion of 24 hours urinary albumin: DMⅠ group (urinary albumin 30 mg), DMⅡ group (urinary albumin 30-300 mg), DMⅢ group (urinary albumin 300 mg), to compare the differences of urinary NAG, RBP and osmolality in each groups; and to observe the relation of the duration of diabetes and the level of HbA 1c with these parameters. Results: Urinary NAG and RBP increased in urinary but urinary osmolality decreased in all patients. The increase of urinary NAG and RBP were also paralleled with the increase of urinary albumin excretion, and there was a remarkable relation between the urinary NAG, RBP and albumin. The urinary levels of NAG, RBP were much higher in cases with long diabetes history and poor glycaemic control than those with short diabetes history and good glycaemic control. Conclusion: There were tubulointerstital damages in early stages of diabetic nephropathy. These findings suggested that good glycemic control, metabolism disturbance correction and detection of markers of diabetic nephropathy are important in early diagnosis and treatment.