Abstract: Objective To investigate the predictive value of body mass index (BMI) combined with waist circumference (WC) for new-onset nonalcoholic fatty liver disease (NAFLD) in patients with type 2 diabetes mellitus (T2DM). Methods This community-based prospective cohort study was conducted among 3501 T2DM patients without NAFLD recruited from the staff of Kailuan Company, who underwent routine physical examination in the year 2006 and 2007, and a total of 2920 subjects were included in the final analysis. According to the baseline BMI and WC, the subjects were divided into group A (with normal BMI and WC), group B (with normal BMI but elevated WC), group C (with elevated BMI but a normal WC) and group D (with elevated BMI and WC). The subjects in the 4 groups were followed for the occurrence of NAFLD by reviewing their reports of physical examinations during the periods of 2008-2009, 2010-2011, 2012-2013, 2014-2015 and 2016-2017. The cumulative incidence of NAFLD was compared across the 4 groups and Cox regression analysis was used to test the correlation of BMI and WC with new onset of NAFLD. Results The cumulative incidence of NAFLD increased progressively in the 4 groups (50%, 66%, 68% and 77%, respectively). Cox regression analysis showed that compared with group A, groups B, C and D had increased risks of NAFLD after adjusting for age, gender and other risk factors, with HR values of 1.62, 1.98 and 2.47, respectively. Conclusion Elevated BMI and WC are both independent risk factors for NAFLD in type 2 diabetic patients, and the combination of BMI and WC has a greater predictive value for NAFLD than either of them alone.