Endocrine Abstracts

A 56 year old man was admitted from psychiatry ward after episode of symptomatic hypoglycaemia with capillary blood glucose of 2.5 mmol/L. His background included CKD on thrice weekly haemodialysis, IHD, stroke, hypertension and paranoid psychosis but not diabetes. He denied taking hypoglycaemics, his oral intake was normal and weight was stable. He had another symptomatic hypoglycamia after 22 hours with venous glucose of 1.5 mmol/L, Insulin 320 mU/L (3.0–17.0) and C-peptide 7935 pmol/L (260–650 pmol/L). Full sulphonylurea screen was negative, and further screening using high performance liquid chromatography (HPLC) to exclude inadvertent drug intake detected metformin but no other hypoglycaemics. A relative had diabetes treated with metformin and repaglinide. He and his family denied drug dipensing error or mix up of tablets. CT abdomen and MRI pancreas showed lobulation of pancreatic head, but no foci of contrast enhancement. Patient did not comply with further investigations including prolonged supervised fast. He was managed conservatively and was discharged with glucometer, PRN dextrogel and glucagon. He did not have any hypoglycaemic episodes during his outpatient follow up for 8 months.

The cause of his hypoglycaemia remains unknown. Exogenous hypoglycaemia induced by repaglinide remains a possibility, supported by psychiatric background, family history of metformin and repaglinide intake, detection of metformin by HPLC, technical limitation of HPLC to detect some drugs and the fact that he did not have further hypoglycaemia. Endogenous hyperinsulinaemia can not be excluded due to non-compliance. Hypoglycaemia due to sulphonylureas and repaglinide should always be considered with high insulin and non suppressed C-peptide levels. Repaglinide is primarily excreted in bile but clearance is reduced in renal impairment and prolonged monitoring of glucose is needed. Where cause of hypoglycaemia is not identified, careful counselling for symptoms and prompt treatment of hypoglycaemia, blood glucose monitoring and long term follow up are essential.