For those with type 2 diabetes, changing course to sulfonylurea drugs to control blood sugar levels is associated with an increased risk of complications compared with staying on metformin, a new study finds.
Metformin is usually the first drug that is used for patients with type 2 diabetes.
Sulfonylureas are the most commonly prescribed “second line” treatment, and often used in combination with metformin. The researchers conclude it’s safer to continue metformin when introducing sulfonylureas rather than switching.
Not very much is known about the specific risk of adding or switching to sulfonylureas compared with staying on metformin treatment alone.
That’s why Professor Samy Suissa at McGill University in Canada, decided to assess whether adding or switching to sulfonylureas was connected to an increased risk of serious complications, compared with remaining on metformin alone in patients with type 2 diabetes.
Researchers analyzed data from the UK Clinical Practice Research Datalink for over 77,000 patients with type 2 diabetes who started metformin treatment between 1998 and 2013. Hospital records were then used to monitor admissions for heart attack, stroke, death, low blood sugar levels.
According to study findings, “adding or switching to sulfonylureas was associated with an increased risk of myocardial infarction, all-cause mortality, and severe hypoglycemia, compared with patients remaining on metformin.”
During an average follow-up period of just over a year, sulfonylurea use (switching and adding combined) was associated with an increased risk of heart attack, mortality, and severe hypoglycemia compared with continuing metformin alone.
Due to the observational nature of the study, and the exact cause and effect cannot be established.
Nevertheless, Suissa and collaborators say their results are highly generalizable and the large sample size allowed the calculation of precise estimates.
“Our study showed an increased risk of myocardial infarction, all-cause mortality, and severe hypoglycemia associated with the use of second-line sulfonylureas compared with remaining on metformin monotherapy,” the authors concluded.
“The associations with myocardial infarction and all-cause mortality were driven by the switching to sulfonylureas and not the addition of sulfonylureas.”
Therefore, they conclude current recommendations on the treatment of type 2 diabetes, continuing metformin when introducing sulfonylureas is safer than switching.