The association between cigarette smoking and diabetic nephropathy in Chinese male patients

To investigate the association between cigarette smoking and the clinicopathological features and renal prognosis of type 2 diabetic mellitus (T2DM) patients with diabetic nephropathy (DN).

A total of 223 T2DM male patients with biopsy-proven DN who received follow-up for at least 1 year were recruited. The patients were divided into two groups based on smoking status: smoking group and non-smoking group. Clinicopathologic differences were analyzed between the two groups. In addition, smokers were divided into two groups of binary analysis based on smoking amounts and two groups of former smokers and current smokers, and subgroups analysis based on age and DR, respectively. The influence of smoking on estimated glomerular filtration rate (eGFR) was estimated using logistic regression analysis and Cox regression on renal outcomes. Renal outcomes were defined by progression to end-stage renal disease (ESRD) or doubling of serum creatinine (D-SCr) level.

Compared with nonsmokers, smoking patients had more moderate decline eGFR (p = 0.032) and tubular atrophy and interstitial fibrosis (p = 0.033). The adjusted logistic regression analysis suggested cigarette smoking was negatively associated with more severe decline eGFR (p = 0.015), especially for patients with DR (p = 0.010) and patients of age ≤ 50 years (p = 0.012) in the subgroup analysis. In the prognosis analysis, no obvious significant risk factor was shown about smoking. Interestingly, it was observed that former smokers had lower levels of plasma glucose and triglycerides than current smokers (both p < 0.05), while smokers with small smoking amounts had lower levels of triglycerides than those with large smoking amounts (p < 0.05).

Cigarette smoking patients with T2DM and DN had more moderate decline eGFR, especially for DN patients with DR, and milder IFTA lesions, although an obviously significant risk factor was not shown about smoking for DN.