I nfections are an ongoing risk for those with diabetes, bearing with it serious or life-threatening complications. Antibiotics, of course, have been the standard pharmacologic treatment for infections. So it was disconcerting when a recent Canadian study showed that one antibiotic, gatifloxacin (Tequin), has significant risk of hypoglycemia (low blood sugar) and hyperglycemia (high blood sugar) in both diabetics and non-diabetics.

Even before the study results were published in the March 30, 2006, issue of The New England Journal of Medicine, the Canadian government issued a warning to consumers that stated that people with diabetes should not use Tequin. Since then, the drug maker Bristol-Myers Squibb has returned the rights of the drug to a Japanese drug company, and Bristol-Myers Squibb stopped selling and manufacturing Tequin as of June of this year. I checked with my local pharmacy (CVS) and although the pharmacist there told me that he had received a bulletin about Tequin, it has not, as of this writing, been removed from the shelves... although, he said that apparently doctors had gotten the message and stopped writing prescriptions for Tequin because he could not remember the last time he filled a prescription.

WHAT ABOUT OTHER ANTIBIOTICS?

The good news is that very few antibiotics carry the same risk, due to differences in how they work, said David N. Juurlink, MD, PhD, one of the study's authors from the University of Toronto. His study did reveal that there was a slightly increased risk of hypoglycemia with levofloxacin (Levaquin), but no such risk was seen with moxifloxacin (Avelox), ciprofloxacin (Cipro) or certain cephalosporin antibiotics (such as cefuroxime).

Dr. Juurlink pointed out, though, that it's important to remember that infections themselves can cause swings in blood sugar, especially for diabetics. It's not always exclusively the drug.

John Mohr, PharmD, at the University of Texas Health Science Center at Houston Medical School, agrees. His own research suggests that the class of antibiotics known as fluoroquinolones (of which Tequin is one and Cipro, Levaquin and Avelox are others) have been more associated with glucose abnormalities than other classes of antibiotics.

DOSING AND KIDNEYS

Another aspect to be aware of in all of this, said Dr. Mohr, is the dosing issue as it relates to kidney function. For fluoroquinolones that are excreted through the kidneys, attention should be paid to the dose, especially for those patients that have impaired kidney function. Diabetics can have impaired kidney function... they may not be able to eliminate the drug properly... and they can be retaining too much of the drug, unless proper dosage reductions are done. In effect, this can create an overdose situation, he said, which could certainly produce adverse events, such as sugar swings.

Diabetics are not the only ones who have impaired kidney function, Dr. Mohr pointed out. Renal function declines with age, so age is a risk factor for these events as well.

SAFETY STRATEGIES

Dr. Mohr suggests that diabetics taking antibiotics should monitor their blood sugar more frequently than usual and be especially aware of symptoms indicating dysglycemia (a blood sugar imbalance). Diabetics are well aware of these, but since sugar imbalance can affect non-diabetics as well, I asked him to enumerate the symptoms.

What to watch for: Increased perspiration... heart palpitations... increased hunger and/or thirst... confusion.

If you experience these symptoms while on a fluoroquinolone, whether you have diabetes or not, you should seek medical care. If you experience sudden changes in mental status or confusion, you should go to an emergency room. However, increased thirst or hunger may not necessarily be due to the fluoroquinolone, and a follow up in your physician's office should suffice.