PURPOSE: Neutrophil-to-lymphocyte ratio (NLR) was widely studied as a prognostic marker in various medical and surgical specialties, but its significance in diabetic kidney disease is not yet established. METHODS: The subjects comprised 199 men aged 73 ± 11 (mean ± standard deviation) years and 187 women aged 77 ± 10 years from a rural hospital. We examined the relationship between NLR calculated by analyzing differential leukocyte count in complete blood picture and renal function evaluated by estimated glomerular filtration rate (eGFR) using the Modification of Diet in Renal Disease Study Group equation and urinary albumin excretion (UAE). RESULTS: NLR was negatively related to eGFR and positively related to UAE. Multiple linear regression analysis using eGFR and UAE as an objective variables, adjusted for confounding factors as explanatory variables showed that NLR (β = - 0.101, p = 0.009) as well as age, body mass index, serum uric acid, and presence of uric acid lowing medication were significantly and independently associated with eGFR, and NLR (β = 0.113, p = 0.031) as well as prevalence of cardiovascular disease, systolic blood pressure, presence of antihypertensive medication, presence of antilipidemic medication, and eGFR were significantly and independently associated with UAE. The multivariate-adjusted odds ratios (95% confidence interval) of NLR for stage 3a (eGFR < 60 mL/min/1.73 m), stage 3b (eGFR < 45 mL/min/1.73 m), and microalbuminuria (UAE ≥ 30 mg/g Cr) were 1.90 (1.02-3.56) and 2.99 (1.28-6.98), and 1.77 (1.04-3.01), respectively. Next, to examine the consistency of the observed association between NLR and eGFR, we performed subgroup analyses. There was a significant interaction (p = 0.006) only between the two groups regarding antihypertensive medication (absence: β = - 0.272, p < 0.001 and presence: β = - 0.029, p = 0.564). CONCLUSIONS: Our data suggested that NLR might be important as a potential factor for evaluating patients with a higher degree of albuminuria among diabetic outpatients.