Smoking and diabetic nephropathy: An updated systematic review and meta-analysis.

OBJECTIVES

Several studies have reported the potential association between smoking and diabetic nephropathy. However, the studies of non-significant association results were against the association between smoking and diabetic nephropathy. Therefore, the relationship between smoking and diabetic nephropathy was still debated and controversial.

METHODS

Prospective cohort studies were included in the current meta-analysis. The tobacco smoking (current smokers or former smokers) and non-smoking groups in the enrolled studies were compared for the hazard ratio (HR) of diabetic nephropathy. Fifteen studies with 221,821 subjects were included in this meta-analysis. Subgroup analysis of the type 1 diabetes and type 2 diabetes groups was also performed individually to investigate the effects of different types of diabetes on the relationship between smoking and diabetic nephropathy.

RESULTS

Current smoking was significantly associated with a greater log HR of diabetic nephropathy [1.44 (1.22-1.70), Z = 4.39]. In addition, former smoking was significantly associated with diabetic nephropathy [log HR = 1.04 (1.03-1.05), Z = 8.02]. The individual subgroup analysis of type 1 diabetes and type 2 diabetes subjects showed that smoking might be both significantly associated with greater log HRs of diabetic nephropathy.

DISCUSSION

Current and former smoking might be the risk factors for diabetic nephropathy in the current meta-analytic results. The phenomenon of such significant associations were discovered in type 1 and 2 diabetes.