Endocrine Abstracts

Background: In the literature there are rare cases of patients with known Type 2 Diabetes Mellitus whom are diagnosed as insulinoma. However a synchronous diagnosis with insulinoma and diabetes for a patient presenting with hypoglycemia symptoms is not an expected condition.

Case: A 79 years-old female patient was sent to our Endocrinology outpatient clinic because of repeating minor and major hypoglycemia attacks. She had no important finding in her background except a history of autoimmune thyroiditis which is held in control with levothyroxine replacement. Her renal and liver function tests were normal in her initial laboratory tests. A prolonged fasting test was performed after hospitalization. At the third hour of fasting she presented hypoglycemia symptoms and her blood sugar was found as 40 mg/dl. Blood samples for plasma c-peptide, insulin and cortisol level measurement were obtained. Her plasma c-peptide was 3 nmol/L and plasma insulin was 101.6 μU/mL, compatible with insulinoma diagnosis while her cortisol levels were high in a manner excluding a possible adrenocortical defficiency. The patient’s urine ketone was negative during this period. Urinary sulfonylurea metabolites were unmeasured because of laboratory inability for the patient who has endogenous hyperinsulinemia and hypoglycemia at the same time. A sudden spontaneous hyperglicema reaching up to 350 mg/dL was observed in the blood sugar controls while the patient was waiting for pancreatic imaging. Insulin infusion therapy was iniated to control blood sugar levels. During that stage HbA1c and anti-insulin autobodies were studied. Her HbA1c was 5.2% and her anti-insulin autoantibodies were negative. In her follow-ups; repeating hypoglycemia attacks were observed despite the interruption of insulin infusion therapy. Her control laboratory tests were again compatible with hypoglycemia accompanied by endogenous hyperinsulinemia. Her pancreas diffusion magnetic resonance imaging revealed a 12 mm hypervascular mass in the tail region suggesting a possible insulinoma. No local invasion signs were observed. After that, pancreatic mass enucleation was performed. Pathological diagnosis was insulinoma (1.1 cm, pStage I, chromogranin (+), synaptophysin (+), insulin (+), mitoses 3/10 HPF and Ki-67 index: 2%). Multiple subcutaneous insulin injection therapy was initiated after the surgical intervention because of high blood sugar results in the follow-ups. Six months after the surgery, the patient is still using basal insulin and metformin, and her last HbA1c level was 7.2%. She does not report any hypoglycemia attacks since surgery.

Conclusion: In the present case we report a rare situation in which the underlying diabetes seem to remain secret possibly because of the variable secretory pattern of insulinomas.