Objective The revised Standards of Medical Care in Diabetes-2018 recommend a less-intensive HbA1c target for elderly individuals than for younger ones. This study aimed to investigate the development and progression of chronic kidney disease (CKD) according to HbA1c levels separately for elderly and middle-aged individuals in a general Japanese population. Methods This was a retrospective cohort study using health checkup data in Iki City, Japan. The participants of the study were 5,554 residents who attended health checkups more than 2 times over 8 years. This study consists of two sets of analyses to determine (1) the effects of HbA1c on the development of CKD among 4,570 subjects who did not have CKD at baseline and (2) the effects of HbA1c on the progression of CKD in 953 subjects with existing CKD at baseline. Results After adjusting for various risk factors, the multivariable-adjusted hazard ratios for development of CKD increased with the HbA1c level: 1.43 for 7-9% and 1.67 for >9% compared with the reference of <7% (p<0.306 for trend). Similar findings were also observed for the progression of CKD: hazard ratios of 2.48 for 7-9% and 2.46 for >9% compared with the reference of <7% (p<0.077 for trend). No significant differences in the effects of HbA1c level on the development or progression of CKD were observed between elderly and middle-aged individuals (p>0.3 for interaction). Conclusion The risks of the development and progression of CKD increased from HbA1c levels of 7% in a general Japanese population. Similar associations were observed for both elderly and middle-aged individuals.
Keywords: CKD; diabetes.