Impact of low-dose acetylsalicylic acid on kidney function in type 2 diabetic patients with elevated urinary albumin excretion rate

Background. Low-dose treatment with acetylsalicylic acid (ASA) is widely recommended to type 2 diabetic patients as primary prevention against cardiovascular disease. High-dose treatment with cyclooxygenase inhibitors reduces urinary albumin excretion rate (AER) in type 1 diabetic patients with micro- or macroalbuminuria. Whether a similar effect on AER exists during low-dose ASA treatment, which may confound the diagnosis and monitoring of micro- and macroalbuminuria in type 2 diabetic patients, remains to be elucidated. Methods. In a randomized, double-blind, crossover trial, 31 type 2 diabetic patients with elevated levels of AER (> 30 mg/24 h) were, in random order, given ASA (150 mg/day) for 4 weeks followed by placebo for 4 weeks with a 2 week washout period or vice versa. At the end of each treatment period AER, glomerular filtration rate (GFR), blood pressure (BP), transcapillary escape rate (TER_alb) of albumin and haemoglobin A_1c (HbA_1c) were measured. Results. The following variables remained unchanged (mean (95% CI) unless otherwise noted) (ASA vs placebo, paired Student's t-test): AER (201 (119-341) vs 205 (124-340) mg/24 h (geometric mean, 95% CI); P=0.78), GFR (103 (94-111) vs 102 (93-110) ml/min; P=0.58), systolic BP (151 (146-158) vs 152 (146-158) mmHg; P=0.68), diastolic BP (87 (83-91) vs 87 (82-91) mmHg; P=0.88), TER_alb (6.3 (5.7-6.9) vs 5.9 (5.1-6.7); P=0.45) and HbA_1c (8.6 (8.1-9.0) vs 8.5 (8.1-9.0)%; P=0.60). Conclusions. Low-dose treatment with 150 mg ASA daily does not have any impact on AER or GFR in type 2 diabetic patients with micro- or macroalbuminuria. Consequently, the widely recommended prescription of low-dose ASA as a primary and secondary prevention strategy against cardiovascular disease in these patients does not confound the diagnosis or monitoring of micro- or macroalbuminuria.