Objective To evaluate the association between birth weight and subsequent risk of type 2 diabetes (T2DM) across two generations in Chinese females.Methods A cross-sectional survey was conducted among 10 324 blood-related females in Shanghai from November 2012 to January 2013.A structured questionnaire was used to collect data about demographic information,birth weight,lifestyle factors and diagnosis of T2DM.Path analysis was performed to estimate the matemal effect of birth weight and diabetes status on their offspring,and mediation analysis was conducted to test whether birth weight mediates the association between maternal and daughters' diabetes status.Results A positive association was observed between maternal and daughters' birth weight.One kg increase in maternal birth weight was associated with an average of 0.335 (95％CI:0.307-0.363) kg elevated birth weight in female offspring.Maternal diabetes status was also related with an average of 0.066 (95％ CI:0.025-0.107) kg increase in birth weight and tripled risk of subsequent T2DM (OR=3.173,95％CI:1.946-5.174) in female offspring.In all subjects aged ≥20 years,no significant relationship was observed between birth weight and risk of T2DM subsequently after adjusting for age.Offspring' s birth weight,as a mediator of maternal and daughters' diabetes status,explained 2.8％ of their association.Conclusion Maternal birth weight and diabetes status may influence their female offspring' s birth weight and subsequent risk of T2DM.