Objective Insulin autoimmune syndrome (IAS) is the third most common cause of spontaneous hypoglycaemia in Japan but very rare in the rest of the world. We aimed to identify factors, which are associated with the occurrence of IAS and which may differ between East Asian and non‐East Asian patients. Design A PubMed search using the search terms ‘insulin autoimmune syndrome’ and ‘Hirata disease’ revealed a total of 287 reports of IAS cases, including one previously unpublished own case. Results Mean age (±standard deviation) was 52 ± 19 years in East Asian and 54 ± 21 years in non‐East Asian patients (p > .05). In both groups, there were more females. Mean body mass index was lower in East Asian than in non‐East Asian patients (23.0 ± 4.3 vs. 27.1 ± 5.6 kg/m2, p < .0001). Postprandial hypoglycaemia was more common in non‐East Asian patients (p < .05). East Asian patients took more frequently antithyroid medications and non‐East Asian patients angiotensin‐converting enzyme (ACE) inhibitors (both p < .0001). Graves' disease and other autoimmune diseases were more frequently observed in East Asian patients (both p < .01). Parameters of glucose metabolism were comparable in both groups, independent of diabetes diagnosis (p > .05), except for insulin that was higher in East Asian compared to non‐East Asian metabolically healthy patients (p < .01). Human leukocyte antigen (HLA)‐DRB1*0406 was the most frequent HLA‐type in East Asian patients (p < .0001), whereas DRB1*0403 and *0404 were more frequent in non‐East Asian patients (both p < .05). Non‐East Asian patients received more secondary treatments, including plasmapheresis and rituximab, whereas medication discontinuation was more common in East Asian patients (all p < .05). Outcome was similar in both groups (p > .05). Conclusions Factors associated with IAS markedly differ between East Asian and non‐East Asian patients, with autoimmune disorders, particularly Graves' disease, antithyroid medications, and HLA‐DRB1*0406 more prevalent in East Asian patients and cardiovascular and plasma cell diseases, ACE inhibitors and HLA‐DRB1*0403 more prevalent in non‐East Asian patients.