A common diabetes drug used to help control blood sugar levels has now been found to lower the risk of kidney failure, according to a new study.
Diabetes is a leading cause of kidney failure. About 1 in 4 adults with diabetes has some form of kidney disease.
The new study tested the drug canagliflozin, which is sold under the brand name Invokana, to see if it could lower the risk of kidney disease when used alongside standard treatments.
Experts welcome this and other medications that target the complications of diabetes, but warn that high costs may limit wider access to these drugs.
The study included 4,401 people, at least 30 years of age, with type 2 diabetes and chronic kidney disease. Researchers randomly assigned people to take either canagliflozin or an inactive placebo.
People were treated on average for 2 1/2 years. The study was stopped early when results showed that the drug was helping.
Compared to people taking the placebo, those on the drug had a 34 percent lower risk of end-stage kidney disease, worsening kidney function, or death due to kidney problems.
End-stage kidney disease included a need for dialysis or transplantation, or signs of kidney failure.
People taking the drug also had a lower risk of cardiovascular death, heart attack, stroke, and hospitalization due to heart failure, compared to the placebo group.
The drug did have some safety concerns as well.
An earlier study of canagliflozin found an increased risk of leg, foot, or toe amputation in people taking the drug.
The new study found that this risk — along with the chance of bone fractures — was similar for the drug and placebo groups.
However, the risk of diabetic ketoacidosis was higher in people taking the drug compared to those taking the placebo. This life-threatening problem occurs in people with diabetes when the body breaks down fat too quickly, causing the blood to become acidic.
The study didn’t include people with very advanced kidney disease or people with kidney disease due to conditions other than type 2 diabetes. More research will be needed to determine if the drug can reduce the risk of kidney disease in these groups.
The results were published April 14 in The New England Journal of Medicine.
The study was funded by the drug’s manufacturer, Janssen, a division of Johnson & Johnson. Many of the authors of the paper work for or consult for the company.
Over the past couple decades, diabetes treatment has shifted beyond just controlling blood glucose levels with insulin shots, diet, and exercise.
“The prevention or delay of progression of complications and preservation of quality of life are goals of diabetes treatment,” said Dr. Lorena Wright, an endocrinologist with UW Medicine in Seattle, who wasn’t involved in the study. “This requires glucose control but also renal and cardiovascular risk reduction.”
Drugs like canagliflozin are part of this new approach to treatment. It’s an SGLT2 inhibitor, which lowers blood glucose by increasing the amount of glucose that the kidneys get rid of in the urine.
Wright said this study confirms the growing evidence that SGLT2 inhibitors have protective effects on the kidneys.
Other doctors welcome medications to treat the complications of diabetes.
“It is of tremendous value to have a drug option which may not only preserve, but also improve kidney function,” said Dr. Minisha Sood, an endocrinologist at Lenox Hill Hospital in New York City, who wasn’t involved in the new study.
Dr. Theodore Strange, associate chair of medicine at Staten Island University Hospital in Staten Island, New York, pointed out that canagliflozin could reduce the number of people with diabetes needing dialysis.
However, he said ongoing follow-up of this and similar drugs will be needed to ensure that their benefits are sustainable.
“I’m always cautiously optimistic with these kind of results,” said Strange, who wasn’t involved in the study.
Wright said unfortunately access to new medications for treating diabetes complications are for the most part restricted by cost.
Invokana costs about $500 to $600 a month in the United States, with no cheaper generic version available.
Out-of-pocket costs for patients will vary depending on their insurance. Some plans, though, may not even cover this drug.
Caremark, a pharmacy benefit manager for many insurance plans, recently removed Invokana from its drug formulary. That means people on these plans wanting to use this drug may end up paying the full price.
People with diabetes already have high medical expenses, spending about $16,750 per year on medical expenses, according to a recent study — $9,600 of this is directly related to diabetes.
On top of this, they’ve had to deal with the skyrocketing price and out-of-pocket costs for insulin.
People without insurance are hardest hit by the cost of medications. But even patients with insurance may not be able to afford the copays for insulin and medications they’re taking for diabetes and its complications.
As a result, “Patients may skip medications or simply may not be able to afford them,” said Wright.
Sood said the hope is that “more meaningful data, such as this new study, will improve insurance coverage for this and similar medications.”
Better coverage of medications to treat the complications of diabetes could help make a dent in the cost of diabetes-related kidney disease. In 2011, this reached almost $25 billion, just among Medicare enrollees.
“Coverage for these medications will reduce costly complications, such as dialysis and hospitalizations,” said Wright, “and will lower morbidity and mortality rates.”