Two population-based, case-control studies show that gatifloxacin increases the risk for both hypoglycemia and hyperglycemia.¹ Researchers conducted 2 population-based, nested, case-control studies in a population of approximately 1.4 million Canadians aged 65 years and older. In the first study, case patients had been treated in a hospital for hypoglycemia after outpatient therapy with a macrolide, a second-generation cephalosporin, or a respiratory fluoroquinolone (gatifloxacin, levofloxacin, moxifloxain, or ciprofloxin.) In the second study, case patients had received hospital care for hyperglycemia. Each case patient was matched with 5 controls, for gender, presence or absence of diabetes, and timing of antibiotic therapy.

Among 788 patients who had been treated for hypoglycemia within 30 days after antibiotic therapy, patients treated with gatifloxacin had an increased risk of hypoglycemia when compared with patients who had received macrolides (adjusted odds ratio, 4.3), and patients treated with levofloxacin showed a slightly increased risk (adjusted odds ratio, 1.5.) No such risk was seen in patients treated with moxifloxacin, ciprofloxacin, or the cephalosporins.

From the same pool, 470 patients were identified who had been treated for hyperglycemia within 30 days of antibiotic therapy. In this group as well, gatifloxacin was associated with a considerably increased risk of hyperglycemia, and no risk was noted with other antibiotics. Risks were similar in the 2 studies, regardless of whether the patients were diabetic or not.

Reflecting on these findings in an editorial, Jerry H. Gurwitz MD, Executive Director of the Meyers Primary Care Institute, doubts that label changes instituted by gatifloxacin’s manufacturers in February are sufficient to protect vulnerable diabetic and elderly patients from harm. He warns that “the safety of patients hinges on the ability of the physician to recall a particular warning concerning an adverse drug effect and to make a mental connection with the clinical characteristics of the patient.”²

1. Park-Wyllie LY, Juurlink DN, Kopp A, et al. Outpatient gatifloxacin therapy and dysglycemia in older adults. N Engl J Med. 2006;354:1352-1361.

2. Gurwitz JH. Serious adverse drug effects—seeing the trees through the forest. N Engl J Med. 2006;354:1413-1415.