Endocrine Abstracts

We present the case of a patient who started having repeated episodes of symptomatic hypoglycemia at the age of 50.

Medical history

Father had type 2 diabetes. Former smoker, moderate alcohol consumption. Chronic otitis media with cholesteatoma, surgically removed. Congenital cataract operated at the age of 3.

Clinical course

At around the age of 50, the patient started having sporadic episodes of sympathoadrenal and neuroglycopenic symptoms, with plasma glucose levels of 60 mg/dl, that ceased after the intake of sugars. The episodes occurred more frequently in the early morning fasting state, but also before meals during daytime. His general practitioner detected a fasting glucose level of 42 mg/dl and HbA1c of 3.3%, refering the patient to Endocrinology. During the following years, a fasting evaluation evidenced hypoglycemia with inappropriately elevated levels of insulin and C-peptide (insuline/glucose ratio 0.61). A CT and an abdominal arteriography didn’t show pancreatic lesions. The patient was diagnosed with endogenous hyperinsulinism without detection of insulinoma. At age 56, the episodes of hypoglycemia became more frequent and treatment with diazoxide was initiated, with dose titration up to 250 mg/day and partial response with a decrease in the number of episodes. Further testing was performed: glicazide was detected in HPLC of a sample obtained during hypoglycemia, but this could not be confirmed in three subsequent analyses; proinsulin levels were elevated; no insulin antibodies were present. Localizing studies were repeated: CT, echo-endoscopy and abdominal arteriography were carried out without findings; and MRI revealed slight contrast enhancement in the head of the pancreas. That same year, another MRI did not confirm such abnormality. During the follow-up, the dose of diazoxide was progressively reduced to 100 mg/day, and remained well-tolerated. Between the ages of 63 and 68, there was a gradual increase in the frequency of episodes of hypoglycemia and a decrease in the associated symptoms. At age 68, the case was reevaluated with a new sulfonylureas analysis that was performed during hospitalization with a negative result, a new localizing study (CT, MRI and echo-endoscopy) without findings and a MODY panel genetic test, which revealed a mutation in GLIS3 gene. This gene can function both as an activator and a repressor of transcription in pancreatic beta cells, which could explain the endogenous hyperinsulinism in our patient.