Endocrine Abstracts

Introduction: Levofloxacin is a fluoroquinolone group antimicrobial agent widely used in the treatment of community- and hospital-acquired infections. There have been reports of glucose homeostasis abnormality associated with the use of fluoroquinolones including gatifloxacin, levofloxacin and ciprofloxacin. This report presents the case of a patient with type 2 diabetes mellitus who developed severe hypoglycemia following oral levofloxacin use.

Case: A 77-year-old female patient was being followed for chronic atrial fibrillation, heart failure, asthma, hypothyroidism, and type 2 diabetes mellitus. For treatment of her diabetes, she was receiving intensive insulin therapy (a total of 110 units daily) and metformin, sitagliptin and empagliflozin. Two months ago, the patient was treated in an external center for COVID pneumonia, and was discharged on oral levofloxacin 500 mg/day two days before admission to our center. Following discharge, the patient developed confusion at home, and her blood glucose level was found to be 52 mg/dl, upon which she was admitted to our clinic for further investigations. We discontinued the antidiabetic medications. Differential diagnosis was performed to identify the causes of hypoglycemia, which ruled out adrenal insufficiency. The detailed history of the patient revealed that her complaints started on the second day of levofloxacin use. Levofloxacin was thought to be the possible cause of hypoglycemia and was discontinued. During the first three days, she had normal blood glucose levels. Starting from day four, her blood glucose started to increase up to 300 mg/dl. She was initially started on basal insulin; basal insulin was gradually increased and insulin aspart boluses were added. The patient was stabilized with basal bolus insulin therapy and was not given oral antidiabetics due to her GFR and serum creatinine levels. Her overall condition remained stable and her complaints regressed. She was discharged with a total daily insulin dose of 82 units (3×14 units of insulin aspart, 40 units of U300 insulin glargine).

Discussion: Levofloxacin-induced hypoglycemia is a rare complication, and although few cases have been reported in previous studies, some patients were reported to have severe and fatal hypoglycemia. Although levofloxacin is widely used, there is limited awareness of its possible hypoglycemic effects. Increased awareness of this side effect of levofloxacin may reduce the mortality and morbidity rates associated with the rare but life-threatening side effect of this widely used antibiotic. When selecting drugs for comorbidities in diabetic patients, it is crucial to consider potential effects of medications on glucose metabolism.