Objective: To investigate the application of urinary neutrophil gelatinase associated lipocalin (NGAL)/creatinineratio in the early diagnosis and assessment of severity of renal injury in patients with type 2 diabetes mellitus (T2DM). Methods: A group of 112 T2DM patients were recruited. Based on urinary albumin/creatinine ratio (UACR), diabetic patients were divided into three groups: 38 cases with normal albuminuria (NA group), 36 cases with minimal albuminuria (MA group) and 38 cases with clinical albuminuria (CA group). And, 32 healthy subjects were served as controls (NC group). Urinary NGAL/creatinine ratio was calculated and compared among the groups and their correlations with other clinical parameters were analyzed. Results: Urinary NGAL/creatinine ratio in T2DM groups [NA, 16.46(6.94-27.07) ng/mg;MA, 20.16(6.76-44.35) ng/mg;CA, 26.89(10.60-56.94) ng/mg] was markedly increased than that in the normal control group [9.13(3.92-17.36) ng/mg] (P<0.05). In the T2DM groups, urinary NGAL/creatinine ratio in CA group was significantly higher than that in NA group (P<0.05). Correlation analysis showed that urinary NGAL/creatinine ratio was positively correlated with UACR, duration of diabetes and glycated hemoglobin (HbA1c) (P<0.05). Conclusions: Urinary NGAL could be an earlier marker than minimal albuminuria for detecting renal injury in T2DM. Furthermore, urinary NGAL level can evaluate the severity of renal injury.