26th May 2025

A 34-year-old woman presents to ED with confusion having been seen lying in her garden by her neighbour.

A 34-year-old woman presents to ED with confusion having been seen lying in her garden by her neighbour. She has a medical history of type 1 diabetes, hypertension, bipolar disorder, CKD and COPD. Her medications include metformin, gliclazide and insulin.  She has had multiple ED attendances before. On review she is sweaty and tremulous and unable to give a coherent history of events. 

Bloods showed Normal U&E, adjusted calcium 2.72mmol/L (2.20-2.60), glucose 1.4mmol/L. 

She is treated with IV dextrose 50% which quickly improves her blood glucose and mental state. 

Her remaining bloods show:

C peptide: undetectable

Serum insulin: 320 mIU/L (normal 2-20 mIU/mL)

What is the single most likely cause of her hypoglycaemia?

Select the SINGLE most appropriate option from the list below. Select ONE option only.