Background: The definitions of contrast-associated acute kidney injury (CA-AKI) are diverse and have different predictive effects for prognosis, which are adverse for clinical practice. Few articles have discussed the relationship between these definitions and long-term prognosis in patients with diabetes. Methods: A total of 1154 diabetic patients who were undergoing coronary angiography (CAG) were included in this study. Two definitions of CA-AKI were used: CA-AKIA was defined as an increase ≥ 0.3 mg/dl or > 50% in serum creatinine (SCr) from baseline within 72 h after CAG, and CA-AKIB was defined as an increase ≥ 0.5 mg/dl or > 25% in SCr from baseline within 72 h after CAG. We used Cox regression to evaluate the association of these two CA-AKI definitions with long-term mortality and calculate the population attributable risks (PARs) of different definitions for long-term prognosis. Results: During the median follow-up period of 7.4 (6.2–8.2) years, the overall long-term mortality was 18.84%, and the long-term mortality in patients with CA-AKI according to both CA-AKIA and CA-AKIB criteria were 36.73% and 28.86%, respectively. We found that CA-AKIA (HR: 2.349, 95% CI 1.570–3.517, p = 0.001) and CA-AKIB (HR: 1.608, 95% CI 1.106–2.339, p = 0.013) were associated with long-term mortality. The PARs were the highest for CA-AKIA (31.14%), followed by CA-AKIB (14.93%). Conclusions: CA-AKI is a common complication in diabetic patients receiving CAG. The two CA-AKI definitions are significantly associated with a poor long-term prognosis, and CA-AKIA, with the highest PAR, needs more clinical attention. © 2020, The Author(s).