Background and objectives: The China National Diabetes and Metabolic Disorders Study [N Engl J Med, 2010] from June 2007 through May 2008, was a cross-sectional study reported that the age-standardized prevalences of total diabetes were 9.7%, accounting for 92.4 million adults with diabetes in China.Taking advantage of this study, we aimed to investigate the prevalence of autoimmune diabetes in China by screening islet autoantibodies.Methods: A nationally representative sample of 46,239 adults, 20 years of age or older, from 14 provinces and municipalities participated in the study.After an overnight fast, participants underwent an oral glucose-tolerance test(OGTT).Previously diagnosed diabetes was determined on the basis of self-report.We further randomly selected 1002 OGTT negative subjects as control, and screened glutamic acid decarboxylase antibodies(GADA), protein tyrosine phosphatase-like protein autoantibodies (1A2A) and zinc transporter isoform 8 autoantibodies (ZnT8A) centrally in 4671 OGTT confirmed diabetic subjects by Islets Autoantibody Standardization Program (IASP) 2012 validated methods.Results: By screening the 3 islet autoantibodies, we found that the prevalence of autoimmune diabetes taking account of 6.6% (310/4671) of the diabetes population, which suggest about 6.1 million adults with autoimmune diabetes in China.Among them, the positivity of GADA, 1A2A, and ZnT8A is 4.1%(190/4671), 1.4%(65/4671), and 1.7%(78/4671), respectively.The population based GADA positivity is obviously lower than the data from clinic based study we reported before [Diabetes 2013].Conclusion: Autoimmune diabetes is prevalent in Chinese.Our raw data showed that China has the biggest autoimmne diabetes population around the world.