A Rare Cause of Severe Hypoglycaemia

Abstract

A 67-year old woman presented with an unwitnessed fall and decreased oral intake. She had a learning disability, hypertension, epilepsy, asthma, chronic iron deficiency anaemia, mild lymphopenia, osteoporosis and treated uterine cancer. After clinical review, she was treated for Hospital-acquired pneumonia (following a recent hospital admission) with possible aspiration. She was noted to have hyponatraemia secondary to dehydration. She was commenced on intravenous Levofloxacin and Metronidazole along with supportive care, based on antibiotic guidance due to her known allergy to penicillin.
On day 3 of admission, she was found unresponsive with a capillary blood glucose of 0.6 mmol/L, which improved with 10% glucose infusion. The low blood glucose was attributed to poor oral intake. However, her serial blood sugar results demonstrated persistent hypoglycaemia for 72h  needing further intravenous glucose infusions. A medication review was undertaken and Levofloxacin was discontinued. After 24hrs of discontinuation, the hypoglycaemic episode resolved. A short synacthen test showed a normal cortisol response. There were no further episodes of hypoglycaemia.

Conclusion

As her persistent hypoglycaemia resolved on discontinuation of Levofloxacin, a diagnosis of fluoroquinolone induced hypoglycaemia was reported to MHRA. Fluoroquinolones are thought to induce hypoglycaemia by increasing the insulin release via blockade of adenosine triphosphate-sensitive K+channels in the β cells of the pancreas. This effect may not be clinically evident in all patients because of physiologic mechanisms that regulate blood glucose levels. 
Health professionals should be aware of the potential risk of severe hypoglycaemia with the use of Fluoroquinolones which are a first or second-line treatment for common infective processes. Fluoroquinolones should be stopped immediately and switch to a non-Fluoroquinolones antibiotic if possible. In elderly patients with compromised oral intake or in those with other comorbidities, regular blood glucose monitoring should be carried out to avoid life-threatening hypoglycaemic episodes.