Objective To investigate the potential association among urinary albumin excretion rate(U_(AER)), 24h ambulatory blood pressure(ABP) and erythrocyte sodium-lithium countertransport(SLC) in non-insulin dependent diabetes mellitus (NIDDM). Methods U_(AER), SLC were determined with radioimmunoassay and modified method of Canessa respectively, and 24h ABP profiles were recorded in 69 NIDDM subjects. Results NIDDM patients with increased U_(AER) had higher prevalence of hypertension and higher prevalence of abnormal circadian rhythm of blood pressure. Blood pressure(BP), particularly nighttime systolic BP was also significantly increased. U_(AER) was positively correlated to mean nighttime BP, mean daytime and 24h systolic BP, while inversely related to day-night dip in systolic BP. However, there was no significant difference in SLC between NIDDM subjects with and without increased U_(AER). Futhermore, neither U_(AER) nor all ABP indices were correlated to SLC. Conclusion Close association exists among diabetic nephropathy and increased BP and abnormal diumal BP rhythm, while either SLC and U_(AER) or SLC and BP is significantly correleted. Increased rate of SLC is not likely a marker for diabetic nephropathy in NIDDM, and it seems not to be involved in the pathogenesis of diabetic hypertension.