Alvin Powers, MD, of Vanderbilt
University in Nashville, TN, who was not involved in the study, was
brave enough to make this statement, "We don't know enough
about those drugs [sulfonylureas]." I thought as long as
these had been around, they should have had more than enough
information, but when it comes to oral diabetes medications,
apparently there is still a lot to learn even when they are now in
generic.
The study compared data from a large
retrospective cohort study of metformin to three commonly prescribed
sulfonylurea drugs. The three drugs were glipizide, glyburide, and
glimepiride. The discovery was a little shocking when diabetes
patients had a 50 percent higher risk of death compared to patients
on metformin. The study, which was funded by drug company Astra
Zeneca shows that apparently the sulfonylureas are more a cause for
concern.
This is speculation on my part, but I
feel that doctors just don't cover the side effects in sufficient
detail. They don't emphasize the warning that these drugs cause low
blood glucose by themselves (hypoglycemia) and if you skip a meal,
skip the medication. This alone could be causing part if not much of
the increase in mortality. Patients that do not understand the
dangers of hypoglycemia will not take the care that needs to be
taken. This is also an area that the certified diabetes educators
seem to gloss over.
I also hope this will give researchers
cause for concern and not to stack so many oral medications. Many
researchers that think the larger the oral diabetes medications
cocktail, the greater glycemic control there should be. Some
researchers may continue to stack oral medications and fail to report
adverse medication events until the adverse events become so great
like they did on the ACCORD study.
Findings, like this study, presented at
medical meetings are typically considered preliminary until published
in a peer-reviewed journal. However, this could still cause
"enormous clinical implications." Apparently,
sulfonylureas have been considered safe and effective. Now we will
need to see if the FDA will require a label warning.
Cost cannot be a distinguishing factor,
as all three sulfonylurea drugs are available in inexpensive generic
forms. Metformin offers an alternative to sulfonylureas as
first-line oral therapy for diabetes and also is available as a
generic.
An enterprise-wide electronic health
record (EHR) system was used to conduct the retrospective study of
diabetic patients who started treatment with one of the sulfonylureas
or metformin from Oct. 24, 1998 to Oct. 12, 2006. The search
produced records for 23,915 patients. About half (12,774) started
treatment with metformin, followed by glipizide (4,325), glyburide
(4,279), and glimepiride (2,537). All patients were adults treated
in outpatient clinics. Investigators excluded patients using insulin,
other injectable diabetes medications, or multiple oral drugs for
diabetes.
The patients had a median follow-up of
2.2 years and 2,546 patients died. This was verified by the EHR or
Social Security Death Index. This is how patients treated with a
sulfonylurea had a mortality hazard ratio of 1.50 compared with
metformin.
Because recent reports suggested
sulfonylurea risk varied in patients with coronary artery disease
(CAD), investigators conducted a separate analysis of 2,721 patients
with a history of CAD. As compared with metformin, patients who
started treatment with glyburide had a 38% increase in the mortality
hazard (HR 1.38), and there was a 41% increased risk in patients
started on glipizide (HR 1.41). Only glimepiride was not associated
with an increased mortality hazard versus metformin.
Dr. Minisha Sood, also an
endocrinologist at Lenox Hill, said that sulfonylureas may fare worse
than metformin because they may "interfere" with
cardiovascular processes that strengthen and protect heart tissue
making it more resilient should a cardiac event occur.
"What's interesting about this
study is that all three sulfonylureas examined led to increased
mortality rates vs. metformin in the entire cohort study, which
included patients without coronary artery disease," Sood
added. "Does this mean that we shouldn't be prescribing
sulfonylureas at all? I think prospective trials are needed to answer
that question, so the jury is still out."
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