Does smoking increase the risk of progression of nephropathy and/or cardiovascular disease in type 2 diabetic patients with albuminuria and those without albuminuria?

Diabetic nephropathy is the primary cause of chronic kidney disease and is associated with increased cardiovascular mortality. Cigarette smoking is probably the most complex and the least understood among the risk factors for chronic kidney disease and cardiovascular disease in diabetic patients. The aim of this study was to determine the impact of smoking on progression of nephropathy and cardiovascular disease in type 2 diabetic patients with albuminuria and those without albuminuria. Methods: This is a prospective study. The Ethics Committee of Morocco's Mohammed V University in Rabat approved the study protocol. Inclusion criteria targeted patients who were type 2 diabetics and who had nephrology follow up for at least 36 months. Results: A total of 671 cases of T2D were included. Mean age of all patients was 65 +/- 11 years and 12.1% were smokers. There was no statistically significant difference between T2D patients with albuminuria according to absence of presence of smoking at the time of enrollment, at 1 year and 3 years of follow-up, concerning the median albumin excretion rate (mg/day): 98 [56-281] vs. 124 [56-323] (p=0.59); 98 [56-281] vs. 124 [56-323] (p=0.15) and 98 [56-281] vs. 124 [56-323] (p=0.52) respectively. There was a statistically significant difference between T2D patients with albuminuria according to absence or presence of smoking at the time of enrollment and the end of follow-up, concerning cardiovascular events: 56 (12.3%) vs. 19 (28.4%) (p<0.001) and 66 (14.5%) vs. 19 (28.4%) (p=0.004) respectively. Conclusion: Smoking remains one of the most important modifiable risk factors for progression of renal and cardiovascular disease in diabetic patients, thus adding to the burden of morbimortality.