ABSTRACT
Objective:To evaluate the association between smoking and the risk of type 2 diabetes (T2DM) incidence among Asian adults based on the prospective studies.Methods:Prospective studies conducted on Asian adults through May, 2019 were retrieved from the following databases: SinoMed, CNKI, VIP, WanFang, PubMed, Web of Science, Embase, and Cochrane Library. Then data were extracted on smoking status, smoking quantity, the number of newly-onset T2DM cases, and effect sizes.Results:A total of 31 studies were included. There were 2 159 787 investigators, 599 340 (27.75%) smokers, and 124 883 (5.78%) T2DM cases identified during the mean follow-up period of 8.3 years. Compared with non-smokers, the combined relativerisk ( RR) and 95% confidence interval ( CI) of current smokers and quitting smokers were 1.52 (1.34- -1.72) ( P<0.001) and 1.22 (1.09- -1.37) ( P=0.047), respectively. The RR and 95% CI of light smokers (<20/day), moderate smokers (20- -29/day), and heavy smokers (≥30/day) were 1.31(1.21- -1.53) ( P=0.001),1.42(1.14- -1.76)( P=0.212), and 2.17(1.50- -3.16) ( P=0.198), respectively. In males and females, the RR and 95% CI were 1.15 (1.08- -1.21) ( P<0.001) and 1.20 (1.11- -1.30) ( P=0.038), respectively. In addition, compared with non-smokers, the RR and 95% CI of current smokers were 1.57 (1.22- -2.03) ( P<0.001) and 1.47 (1.30- -1.66) ( P=0.063) during the follow-up periods of less than and more than 8.0 years, respectively, while the RR and 95% CI of quitters were 1.23 (1.06- -1.43) ( P=0.091)and 1.20 (1.07- -1.34) ( P=0.041), respectively. Conclusions:Prospective studies based on Asian adults have shown that smoking significantly increases the risk of diabetes incidence. That is, as cigarette consumption increases, the risk of diabetes increases accordingly. Moreover, compared to males, the risk for female smokers is greater. In addition, longer durations of smoking cessation are associated with a lower risk of T2DM.