Objective To explore the clinical characteristics, early diagnosis and identification, treatment and prognosis of non-hypoglycemic insulin autoimmune syndrome (NHIAS) caused by methimazole, provide a basis for clinical diagnosis and treatment of NHIAS, and conduct a retrospective analysis of relevant case reports and literature on NHIAS. Methods This article reported the diagnosis and treatment process of an insulin autoimmune syndrome without hypoglycemia in a child with Graves' disease who was using methimazole, and reviewed relevant literature.Results In a case of a child with Graves' disease who was using methimazole, it was observed that IAA levels increased, insulin levels rose, and insulin-c-peptide separation occurred, without any signs of hypoglycemia. After discontinuing methimazole and treating with propylthiouracil, follow-up for one year showed that IAA gradually returned to normal. NHIAS is extremely rare. This article reviewed the literature and summarizeed 4 cases of NHIAS patients. The youngest was 53 years old and the oldest was 72 years old. All had type 2 diabetes and a history of oral hypoglycemic drugs or insulin analogues. Among them, 3 patients were considered to be induced by endogenous or exogenous insulin, and 1 patient was induced by a health supplement drug. All presented with poor blood sugar control and hyperglycemia. 2 cases spontaneously improved after discontinuing the related drugs, and 2 cases were relieved after adding oral glucocorticoids treatment.Conclusion Methimazole can cause non-hypoglycemic type IAS, which is often overlooked in clinical practice and has the risk of increasing persistent hyperglycemia. Through proper early identification, diagnosis and treatment in clinical settings, a favorable prognosis can be achieved