AIMS: This study aimed to assess the relationship between hemoglobin glycation index (HGI) and risk of rapid kidney function decline (RKFD) in diabetic patients. METHODS: HGI was calculated as actual measured HbA1c minus predicted HbA1c. RKFD was defined as a 30 % decline in estimated glomerular filtration rate during follow-up. Participants were categorized into three groups based on HGI levels: lower (HGI ≤ -0.55), medium (-0.55 <
HGI ≤ 0.22) and higher (HGI >
0.23). To understand the association between HGI and risk of RKFD in diabetic patients, directed acyclic graph were drawn and multivariate Cox proportional hazards models were used to adjust for covariates. RESULTS: During a median follow-up of 4.0 years, RKFD occurred in 43 patients (6.3 %) with diabetes. After adjusting for potential confounders, Compared to the lower-HGI group, the hazard ratios for RKFD were 1.75 (95 % confidence interval [95 % CI]: 0.72, 4.25) and 2.64 (95 % CI: 1.12, 6.21) in the medium- and higher-HGI groups, respectively. HGI showed a linearly associated with RKFD (P CONCLUSION: Higher HGI may be associated with an increased risk of RKFD in diabetic patients.