Cigarette Smoking Is Associated With Low Glomerular Filtration Rate in Male Patients With Type 2 Diabetes: Response to Saito et al.

We thank Saito et al. (1) for their interest and comments regarding our recent article (2). They suggest that the absence of positive correlation between the number of cigarettes smoked per day and severity of nephropathy, as expressed by low glomular filtration rate, might be due to the exclusion of ex-smokers in the analysis. This is possible, given the fact that some studies (3,4) (though not all [5]) including ex-smokers have found the above-mentioned correlation. In fact, both options (i.e., ex-smokers being either included or excluded) have their own rationale (3–6). In our specific context, we decided to design a study aimed at investigating the role of current smoking in modulating the risk of having low glomular filtration rate. Including ex-smokers could weaken the result obtained and conceal the role played by exposure to tobacco smoke on oxidative stress, as we have shown. However, we do acknowledge that the alternative approach, including ex-smokers, would have been equally appropriate if aimed at also determining the effect of previous smoking habit.