Objective To investigate the proportion of latent autoimmune diabetes in adult (LADA) in patients with type 2 diabetes mellitus. Methods A total of 178 patients with type 2 diabetes mellitus were classified by body mass index (BMI) levels. Fasting plasma C-peptide, glutamic acid decarboxylase antibody (GAD65), and islet cell autoantibody (ICAs) were detected. Results The proportion of LADA in patients with type 2 diabetes mellitus of angular group and normal group were 5.62%(10/178),1.65%(3/178)respectively.No patient was LADA in overweight or obese group. The total proportion of LADA in the present study was 7.31%, which was significantly lower than the proportion (10.0%) reported by Global Partnership for Effective Diabetes Management but higher than the proportion of 6.0% reported by several studies in China. Conclusion LADA in patients with type 2 diabetes mellitus should be taken into account in clinical practice.