Congenital hyperinsulinism can be resistant to diazoxide treatment due to genetic mutations. The most common cause is mutations in the KATP channel genes, leading to severe hypoglycemia in newborns. Genetic testing and imaging can help locate focal lesions for surgery. Another cause is mutations in the GCK gene, which can result in uncontrollable hypoglycemia. Some cases remain unknown genetically. The main goal is to identify focal hyperinsulinism for surgery and find effective treatments for diffuse cases.