Oct. 11 (UPI) -- A class of Type 2 diabetes drugs called glitazones is linked to a 22% reduced risk of dementia, according to a new study led by the University of Arizona.
The researchers said this drug class, also known as thiazolidinediones or TZDs, which helps insulin work better, may effectively prevent dementia in patients at high risk who have mild or moderate Type 2 diabetes.
The scientists urged prioritizing their findings and conducting more clinical studies to see whether TZDs can be repurposed to fight dementia.
Separately, Cleveland Clinic researchers said Tuesday in the journal Cell Reports Medicine that they have identified metformin, a common diabetes medication, as a possible treatment to repurpose for atrial fibrillation. The condition can lead to stroke and heart failure.
Repurposed drugs may take significantly less time to test and obtain regulatory approval since much information is already vetted, the scientists noted.
Also, according to the University of Arizona-led study, published Tuesday in the British Medical Journal's BMJ Open Diabetes Research & Care, patients with Type 2 diabetes who take the drug sulfonylurea may be at an elevated risk of dementia, compared with people who take metformin or TZDs to treat the widespread illness.
The researchers urged regular monitoring of cognitive functioning in this population, and said taking sulfonylurea with either metformin or TZD may partially offset this effect. These findings may help inform medication selection for elderly patients with diabetes at high risk of dementia, they added.
Nationwide, more than 37 million Americans have diabetes, or about 1 in 10 Americans, and roughly 90% to 95% of them have Type 2 diabetes that tends to develop in people over age 45, the Centers for Disease Control and Prevention says.
Dr. Robert Gabbay, the American Diabetes Association's chief science and medical officer, told UPI in an email that the Arizona-led study is "interesting" and shows an association between the use of TZDs and risk of dementia.
However, Gabbay cautioned that such studies don't prove cause and effect, "and one can imagine a number of other reasons for the association." For example, he said people may have hypoglycemia, or low blood sugar, "which we know can be a risk factor for dementia."
He added: "Since people were not randomized to the different treatments, there may be other factors about people that were given TZDs that could explain why this group did better."
"Bottom line, this is an interesting study that should stimulate further research to identify factors to lower the risk of dementia in diabetes," Gabbay said.
"We know that people with type II diabetes are at greater risk for dementia and one can lower that risk by paying attention to the ABCs -- A1c, blood pressure and cholesterol as risk factors for vascular disease, which is a leading cause of dementia."
The TZD research included nearly 560,000 eligible military veterans with Type 2 diabetes, averaging 65 years old and free of dementia, receiving care in the Veterans Affairs Healthcare System. They were assigned to one of three treatments: sulfonylurea, TZDs or metformin.
After at least one year of treatment, taking TZD alone was associated with a 22% lower risk of all-cause dementia compared with taking metformin. There was an 11% lower dementia risk for people using metformin and TZD dual therapy. But the risk of dementia was 12% higher for people taking sulfonylurea alone.
The researchers suggested that people with Type 2 diabetes who take sulfonylurea might supplement it with either metformin or TZD to potentially partially offset this effect of increased dementia risk.
The findings may help with medication selection for elderly diabetic patients at high risk of dementia, they added.
According to the American Diabetes Association, TZDs or glitazones were first introduced to treat Type 2 diabetes in 1996, when troglitazone received Food and Drug Administration approval.
Subsequently, troglitazone was withdrawn from the market in 2000 because of rare, but serious, liver injury arising from its use. But the diabetes association said two other glitazones, called pioglitazone and rosiglitazone, continue to be widely used by clinicians.
The diabetes group's website noted that glitazones have been shown to have the potential to significantly reduce the risk of cardiovascular disease in diabetes -- as do metformin and insulin.
Several combination drugs also contain TZDs, which have been linked to cases of fluid retention, weight gain, kidney problems and heart failure, according to The Diabetes Council.