Endocrine Abstracts

Contracts with primary care encourage screening for diabetes and as a result a fasting blood glucose is frequently performed on asymptomatic patients. During the last year three such patients were found to have significant hypoglycaemia with elevated c-peptide levels and were referred for further investigation.

The first, a 50 year old woman, developed significant hypoglycaemia 22 hours into a fast with elevated c-peptide and insulin levels. A CT scan of her pancreas failed to demonstrate a lesion but a 15 mm by 8 mm lesion in the pancreas was demonstrated on endoscopic ultrasound. She was completely asymptomatic prior to the discovery of her insulinoma but later became aware when her blood sugar was low.

The second and third cases were a 36 year old man and a 73 year old man. Both had a low screening blood glucose and a high c-peptide (case 2: glucose 2.7 mmol/l; c-peptide 1344 pmol/l, case 3: glucose 2.2 mmol/l; c-peptide 3069 pmol/l). Both were asymptomatic throughout a 72 hour fast and the bloods at 72 hours revealed hypoglycaemia with ketotic hypoinsulinaemia.

Screening for diabetes has resulted in asymptomatic hypoglycaemia being detected. Experience from case 1 has taught us that this cannot be ignored and should be formally investigated. Insulinoma presenting in this way is very unusual.