Background There were few studies to explore the relationship between hemoglobin A1c (HbA1c)and contrast-induced acute renal injury (CI-AKI)in patients with type 2 diabetes mellitus (T2DM). Methods Two hundred seventy-nine patients with T2DM undergonging elective cardiac catheterization from Dongguan Kanghua Hospital were recruited. Patients were classified into quartiles based on HbA1c ( < 6.30%, 6.30- 6.70%, 6.71-7.70, and > 7.70%). Baseline data, CI-AKI incidence and in-hospital outcomes were compared between the groups. Logistic regression was used to assess the relationship between HbA1c and CI-AKI. Results CI-AKI occurred in 26 (9.3%)patients. CI-AKI incidences of HbA1c quartiles were 4.6 % (3 / 65), 2.8%(2 / 71), 12.3%(9 / 73) and 17.1%(12 / 70) (P = 0.003), respectively. There were no significant differences in in-hospital death or required renal replacement therapy among the four groups. Univariate logistic analysis showed that HbA1c was related with CI-AKI (OR = 1.319, 95%CI:1.078-1.615, P = 0.007). Multivariate analysis found that after adjusting eGFR < 60 ml / min / 1.73 m 2 , age > 70 years and anemia, HbA1c ≥7% was still a significant independent risk factor for CI-AKI in patients with T2DM. Conclusions HbA1c is significantly associated with CI-AKI. HbA1c ≥7% may increase the risk of CI-AKI in patients with T2DM undergoing elective cardiac catheterization. Background There were few studies to explore the relationship between hemoglobin A1c (HbA1c) and contrast-induced acute renal injury (CI-AKI) in patients with type 2 diabetes mellitus (T2DM). Methods Two hundred seventy-nine patients with T2DM undergone elective cardiac Patients were classified into quartiles based on HbA1c (<6.30%, 6.30-6.70%, 6.71-7.70, and> 7.70%). Baseline data, CI-AKI incidence and in-hospital outcomes were compared Results CI-AKI incidences of HbA1c quartiles were 4.6% (3/65), 2.8% (2 of 71), 12.3% (9 of 73) and 17.1% (12 of 70) (P = 0.003), respectively. There were no significant differences in in-hospital death or required renal replacement therapy among the four groups. logistic analysis showed that HbA1c was related with CI-AKI (OR = 1.319, 95% CI: 1.078-1.615, P = 0.007) Multivariate analysis found that after adjusting eGFR <60 ml / min / 1.73 m 2, age> 70 years and anemia, HbAlc ≥7% was still a significant independent risk factor for CI-AKI in patients with T2DM. Conclusions HbA1c is significantly associated with CI-AKI. HbA1c ≥7% may increase the risk of CI-AKI in patients with T2DM undergoing elective cardiac catheterization.