Johnson & Johnson's type 2 diabetes drug Invokana significantly reduced the risk of serious heart problems in patients with established heart disease or at elevated risk in a pair of large studies, according to data presented at a medical meeting on Monday.

The medicine also led to a reduced risk of hospitalization for heart failure and protection against kidney function decline. But the risk of amputations, particularly of toes or feet, was double versus placebo in the studies of 10,142 patients with type 2 diabetes.

On the study's main goal Invokana, known chemically as canagliflozin, reduced the combined risk of heart-related death, nonfatal heart attack and nonfatal stroke by a statistically significant 14 percent compared with placebo.

"What we actually got here was not just evidence of safety but evidence of benefit," said lead investigator Bruce Neal, professor of medicine at the University of New South Wales Sydney.

"It's a really positive result. This (heart disease) is the main thing that people with diabetes die from," said Neal, who presented the data at the American Diabetes Association meeting in San Diego.

The study was required to prove Invokana did not cause heart complications. The expectation bar was raised, however, after rival drug Jardiance from Eli Lilly and Co and Boehringer Ingelheim in 2015 demonstrated heart protective qualities in a similar large trial. Reduction of heart-related death is now included in the Jardiance label.

"We look forward to working with the FDA and regulators around the world with respect to getting this in the label," James List, head of cardiovascular and metabolism for J&J's Janssen unit, said of the new data.

Two-thirds of patients had confirmed heart disease and the rest were deemed at high risk. They were followed for an average of about four years.

The number of amputations was small but about double that of the placebo group. A warning of increased amputation risk was added to Invokana's prescribing label after it was discovered by safety monitors during an interim analysis of the study.

"Care is warranted in the use of canagliflozin in patients at risk for amputation," a New England Journal of Medicine article on the study said.

Invokana is the market leader among a newer class of type 2 diabetes treatments called SGLT-2 inhibitors, along with Jardiance and AstraZeneca Plc's Farxiga. They work by removing blood sugar through the urine.

Results from a large Farxiga heart safety trial are expected in 2019.

"I think we're going to see much greater use of canagliflozin and the class in type 2 diabetes," Neal said.

Invokana and related combination treatment Invokamet had sales $284 million in the first quarter, J&J reported.