Effects of smoking and its cessation on creatinine- and cystatin C-based estimated glomerular filtration rates and albuminuria in male patients with type 2 diabetes mellitus: The Fukuoka Diabetes Registry

Cigarette smoking is an important modifiable risk factor for lifestyle diseases. The smoking rate remains high, and the prevalence of diabetes mellitus is increasing in Asian countries; however, few studies have examined the effects of smoking on chronic kidney disease (CKD) in Asian diabetic patients. The aim of the present study was to investigate the association between smoking and its cessation with CKD and its components in patients with type 2 diabetes. A total of 2770 Japanese male patients with type 2 diabetes aged ≥20 years were divided according to the amount of cigarette smoking and the years since cessation. The associations with CKD, the urinary albumin-creatinine ratio (UACR) and the estimated glomerular filtration rate (eGFR) were cross-sectionally examined. The proportions of CKD and the mean UACR dose-dependently increased with increases in both the number of cigarettes per day and the Brinkman index compared with the never smokers. The creatinine-based eGFR also increased with increases in the amount of smoking, whereas the cystatin C-based eGFR decreased, and their average did not significantly change. These parameters exhibited inverse associations with the years after smoking cessation compared with the association with the amount of smoking. A dose-dependent association of active smoking and a graded inverse association of the years since quitting with CKD enhance the merit of smoking cessation in patients with type 2 diabetes.