Abstract: Objective To analyze the clinical data of patients with insulin autoimmune syndrome (IAS),so as to improve the clinician's understanding of IAS and reduce the risk of misdiagnosis. Methods Nineteen cases of IAS diagnosed in the endocrinology department of the first medical center in Chinese PLA General Hospital from January 2010 to December 2019 were reviewed.Their clinical data,including sex,age of onset,induced drug,course of disease,biochemical indicators,treatment and prognosis were analyzed. Results Of the 19 IAS patients,there were 12 males and 7 females,with an average age of (62.53±10.60) years.IAS was often associated with other autoimmune endocrine diseases,and autoimmune thyroid disease was more common (47%).Most IAS patients had a history of taking sulfhydryl drugs (7/19),and exogenous insulin use (6/19).Serum IAA was positive in 19 patients with IAS.OGTT test showed IAS patients had the lowest level of glucose and c-peptide while fasting,and increased signigicantly at 1 h and at 2 h (P<0.05),then decreased to the baseline level.However,no statistical difference was found in insulin over time (P>0.05).In classical IAS patients,the lowest blood glucose was (2.81±1.14) mmol/L,insulin 2101.50 (787.60,7589.00) mU/L,and in non-classical IAS patients,the lowest blood glucose was (2.73±0.39) mmol/L,insulin 1347.50 (475.00,3158.88) mU/L,showing no statistical significance between the two groups (P>0.05).HLA-DR4 alleles in one patient were HLA-DRB1 *0403,*0701 and DQB1 * 0302,*0202.The treatment included dietary modifications in 4 patients,glucosidase inhibitors in 8 cases,glucocorticoids in 7 cases.The hypoglycemia symptoms in most patients could be relieved in 3-6 months. Conclusion IAS is more likely to occur in the elderly,often complicates with autoimmune diseases.Sulfhydryl drug is the most common inducing factor.IAS can be relieved by removing the inducement and adjusting diet.If necessary,glucosidase inhibitor,glucocorticoid should be given.