Antibiotics May Trigger Blood Sugar Swings

Diabetes patients may be at risk of severe blood sugar problems if they take fluoroquinolones

/ Author:  / Reviewed by: Robert Carlson, M.D Beth Bolt, RPh

(RxWiki News) Fluoroquinolones are commonly prescribed to treat urinary tract infections and other illnesses. Recently, these antibiotics have been shown to cause potentially harmful side effects.

In August, the US Food and Drug Administration required the drug labels and Medication Guides for antibiotics called fluoroquinolones to be updated to better describe the possible side effect of serious nerve damage.

Researchers recently found that patients with diabetes who took oral fluoroquinolones were more likely to have serious blood sugar fluctuations compared to diabetes patients who took other types of antibiotics.

Abnormal blood sugar levels can lead to unconsciousness, seizures, heart attack, stroke and other severe health problems in patients with diabetes.

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Mei-Shu Lai, MD, PhD, at the Institute of Epidemiology and Preventive Medicine, College of Public Health at the National Taiwan University in Taipei, led this analysis of data on about 78,000 individuals with diabetes in Taiwan.

Using records from Taiwan’s national insurance program, the scientists reviewed patient use of antibiotics and then looked for emergency room visits or hospitalizations because of abnormal blood sugar levels that occurred within 30 days of taking the antibiotics.

Three types of antiobiotics were examined: fluoroquinolones (levofloxacin, brand name Levaquin; ciprofloxacin, brand names Cipro and Cipro XR; moxifloxacin, brand name Avelox), second-generation cephalosporins (cefuroxime, brand names Ceftin and Zinacef; cefaclor, brand name Raniclor; cefprozil, brand name Cefzil) and macrolides (clarithromycin, brand names Biaxin and Biaxin XL; azithromycin, brand names Zithromax, Zmax and Z-Pak).

The researchers observed that diabetes patients taking oral fluoroquinolones were more likely to have severe blood sugar swings than diabetes patients taking antibiotics in other classes. The biggest risk was associated with moxifloxacin.

When it came to hyperglycemia (high blood sugar), the researchers noted a rate of 6.9 per 1,000 among those taking moxifloxacin, 3.9 per 1,000 for levofloxacin and 4.0 per 1,000 for ciprofloxacin. Rates of hypoglycemia (low blood sugar) were 10.0 per 1,000 for moxifloxacin, 9.3 per 1,000 for levofloxacin and 7.9 per 1,000 for ciprofloxacin.

The other classes of antibiotics were linked to less risk, with rates of hyperglycemia at 1.6 per 1,000 for those taking antibiotics in the macrolide class and 2.1 per 1,000 for those taking antibiotics in the cephalosporin class. When it came to hypoglycemia, incidence per 1,000 was 3.7 for macrolides and 3.2 for cephalosporins.

These blood sugar abnormalities can lead to serious health problems, including irreversible brain damage or even death.

Previous studies have already shown that fluoroquinolones may be linked with blood sugar abnormalities (called dysglycemia), as well as with tendon rupture, heart arrhythmia (a problem with the rhythm of heartbeat) and other side effects.

In 2006, gatifloxacin, which is in the fluoroquinolone class, was pulled from the US market due to the risk of blood sugar abnormalities.

Dr. Lai and her team were especially concerned since fluoroquinolones are increasingly used to treat urinary tract infections, community-acquired pneumonia and other illnesses.

“Clinicians should consider these risks when treating patients with diabetes and prescribe fluoroquinolones cautiously,” the authors wrote.

Maggie Elyasnik, PharmD, a registered Pharmacist and the Director of Operations at Uptown Drug and Gift Shop, an independent pharmacy located in downtown Los Angeles, told dailyRx News that this study highlighted concerns about moxifloxican but not necessarily all fluoroquinolones.

“The study is very effective at showing that moxifloxacin can cause dysglycemia; however, a class generalization is a bit more difficult to make,” said Elyasnik. “This study may be showing a difference in liver enzyme metabolism of moxifloxacin, which is leading to dysglycemia.”

She added, however, that there are other reasons to avoid over-prescribing fluoroquinolones besides concerns over blood sugar levels.

“The overuse of fluoroquinolones can lead to multi-strain drug resistance,” said Elyasnik. The Centers for Disease Control and Prevention (CDC) states that “...resistance to quinolones limits drug selection for treatment of many infections.”

This study was published in August in Clinical Infectious Diseases.

Review Date: 
August 31, 2013
Last Updated:
September 3, 2013