the incidence of insulinoma peaks at 3060 years of age and is more frequent in women ( 1 , 2 ) . its estimated incidence is approximately four cases per million individuals per year ( 1 ) . insulinoma are generally small ( < 2 cm ) and usually not multiple ( 90% ) . only 515% are malignant , and they almost invariably occur only in the pancreas , distributed equally in the pancreatic head , body , and tail ( 3 ) . the most common clinical symptoms are due to the effect of hypoglycemia on the central nervous system ( glycopenic symptoms ) and include confusion , headache , disorientation , seizure ( 4 ) , visual difficulties , irrational behavior , and even coma ( 5 ) . in addition , most patients have symptoms due to excess catecholamine release secondary to the hypoglycemia , including sweating , tremor , and palpitations . characteristically , these attacks are associated with fasting . the diagnosis of insulinoma requires the demonstration of an elevated plasma insulin level at the time of hypoglycemia . the most reliable test to diagnose insulinoma is a 72 hour fasting serum glucose , c - peptide , proinsulin , and insulin measurements every 48 h. if at any point the patient becomes symptomatic or glucose levels are persistently below < 2.2 mmol / l ( 40 mg / dl ) , the test should be terminated and repeat samples for the above studies should be obtained before glucose is given . generally 7080% of patients will develop hypoglycemia during the first 24 h and 98% by 48 h ( 3 ) . the combination of proinsulin levels ( normal in exogenous insulin / hypoglycemic agent users ) , c - peptide levels ( low in exogenous insulin users ) , antibodies to insulin ( positive in exogenous insulin users ) , and measurement of sulfonylurea levels in serum or plasma will allow the correct diagnosis to be made ( 3 ) . unlike most endocrine pancreatic tumors , the majority ( 90% ) of insulinoma are benign and solitary , and only 10% are malignant . however , tumors located close to the main pancreatic duct and large ( > 2 cm ) tumors may require a distal pancreatectomy or pancreaticoduodenectomy ( 6 ) . sometimes , the lesions are unresectable or metastasis to the liver or regional lymph node . in such cases , the treatment approach is variable depending on the extent of metastasis and functional status of the patient . medical therapy may be considered for the non surgical patient and approach to control hypoglycemia events by decreasing insulin production or antagonizing insulin effect at receptor level . diazoxide is the most commonly used oral medication to control hypoglycemia but it causes side effects includes edema and excessive hair growth ( 7 ) . these agents also offer some tumor regression but are not as effective as surgery ( 8 , 9 ) . alternatives to medical therapy include , external beam radio therapy can produce high rates of symptom palliation and freedom from local progression in patients who are not candidates for surgical resection ( 10 , 11 ) . surgical resection of tumor should be considered in limited number of hepatic metastases without excessive local tumor burden and which have acceptable liver function test ( 12 ) . in limited case reports , hepatic artery selective chemoembolization , which predominate supplies cancer hepatocytes , is frequently applied as a palliative technique in patients with symptomatic hepatic metastases who are not candidates for surgical resection ( 13 , 14 ) . alternative approaches include radiofrequency ablation and cryoablation and are applicable techniques for smaller lesions , but their long - term efficacy remains uncertain ( 15 ) . limited randomized controlled trials , and rare incidence of disease with little literature data available , have limited systemic chemotherapy approach for metastatic disease , but well - differentiated pancreatic tumors do respond to cytotoxic chemotherapy including streptozotocin and doxorubicin , and have a combined biochemical and radiographic response rate of 69% and a medical survival of 2.2 years ( 16 ) . there are no evidence - based guidelines for follow - up after resection of a malignant insulinoma but they generally include complete history and physical examinations every 36 months and imaging study for recurrence of disease . . it should be one of the working diagnoses in young patients with multiple events of hypoglycemia . insulinomas are generally 90% benign tumors with excellent surgical result and have good long term prognosis . the authors have not received any funding or benefits from industry or elsewhere to conduct this study .
insulinoma is an exceedingly uncommon pancreatic islet cell neuroendocrine tumor . 
 the estimated incidence is approximately four cases per million individuals per year and accounts for 60% of islets cell tumors . 
 it causes glycopenic symptoms which includes headache , feeling irritable , confused , seizure or coma and leads to catecholamine excess which includes rapid heartbeat , sweating , palpitations and feelings of hunger . 
 early detection of the tumor prevents recurrent episodes of lethal hypoglycemia .