We performed a time series analysis to investigate the potential association between exposure to ambient air pollution and type 2 diabetes (T2D) incidence in the Chinese population. Monthly time series data between 2008 and 2015 on ambient air pollutants and incident T2D (N = 25,130) were obtained from the Environment Monitoring Center of Ningbo and the Chronic Disease Surveillance System of Ningbo. Relative risks (RRs) and 95% confidence intervals (95% CIs) of incident T2D per 10 μg/m 3 increases in ambient air pollutants were estimated from Poisson generalized additive models. Exposure to particulate matter < 10 μm (PM 10 ) and sulfur dioxide (SO 2 ) was associated with increased T2D incidence. The relative risks (RRs) of each increment in 10 μg/m 3 of PM 10 and SO 2 were 1.62 (95% CI, 1.16–2.28) and 1.63 (95% CI, 1.12–2.38) for overall participants, whereas for ozone (O 3 ) exposure, the RRs were 0.78 (95% CI, 0.68–0.90) for overall participants, 0.78 (95% CI, 0.69–0.90) for males, and 0.78 (95% CI, 0.67–0.91) for females, respectively. Exposure to PM 10 and SO 2 is positively associated with T2D incidence, whereas O 3 is negatively associated with T2D incidence.