: A 62-year-old woman was admitted to our hospital because of unconsciousness and hypoglycaemia. She had a history of weakness and fatigue after postpartum haemorrhage in 1983. Unfortunately, she was not diagnosed with Sheehan's syndrome and did not receive sufficient professional treatment due to the limited medical resources in her hometown. A laboratory examination at the local hospital revealed severe hypoglycaemia (1.8 mmol/L) with relatively low serum potassium (2.9 mmol/L). The woman appeared twice in the hospital with cardiac arrest, and her medical history, and the later laboratory investigations were consistent with Sheehan's syndrome. Empty sella was also found by magnetic resonance imaging (MRI). We conclude that Sheehan's syndrome may lead to cardiac arrest with the complication of hypokalaemia and deserves the vigilance of clinicians.