Clinical Case Study

Hypoglycemia precipitating prolonged QT interval and myocardial ischemia in a patient with coronary heart disease and renal failure

Jane Foster, Paul A Baillie & W David Strain

Diabetic Hypoglycemia January 2012, Volume 4, Issue 3: page 9-11

Abstract

A 75-year-old lady with end-stage renal nephropathy attributed to type 2 diabetes and ischemic heart disease was admitted as a medical emergency with right lower lobe pneumonia. In addition to antibiotic therapy, her dose of isophane insulin was increased by 20%. The following morning she became acutely unwell with prominent autonomic symptoms and chest tightness. Her ECG demonstrated anterolateral ischemia with a prolonged QT interval and her blood glucose was 2.7 mmol/l (48.6 mg/dl). She was treated with intravenous and oral dextrose and her symptoms resolved. Her ECG demonstrated resolution of the anterolateral changes, however the prolonged QT interval persisted for 48 hours. This was associated with a rise and fall in her serum Troponin T measurement, peaking at 83 ng/l (normal range 0–14 ng/l). Her insulin dose was restored to the previous amount and her recovery was uncomplicated. This case highlights the increased risk of hypoglycemia in patients with end-stage renal disease who have impaired renal clearance of insulin, and the subsequent risk of hypoglycemia provoking myocardial ischemia.

Key words: hypoglycemia, diabetes, ECG, renal disease, myocardial ischemia, cardiac arrhythmia