A new drug developed by Merck & Co and Pfizer Inc won U.S. approval on Wednesday to treat type II diabetes, the Food and Drug Administration(FDA) said, adding another competitor to a growing class of treatments.

The oral drug, known generically as ertugliflozin, will be sold under the brand name Steglatro and compete with AstraZeneca Plc’s Farxiga, Johnson & Johnson’s Invokana and Eli Lilly and Boehringer Ingelheim’s Jardiance.

All four drugs belong to a class known as SGLT2 inhibitors, which work by causing patients to expel excess glucose through urine.

Merck and Pfizer won approval for Steglatro as a single therapy and in fixed-dose combinations with Merck’s diabetes drug Januvia or with metformin, an older generic treatment typically given to newly diagnosed patients. Those will carry the brand names Steglujan and Segluromet, respectively.

The approvals and prescribing information were listed on the FDA and Merck websites.

The companies, in an emailed statement, said they expect to make the medicines available in early 2018. Under the collaboration Merck, which already has a sizable diabetes sales force, will sell the drug in the United States.

As type II diabetes progresses, many patients need additional treatments to better control blood sugar levels.

Januvia is the top-selling drug in a class known as DPP-4 inhibitors. The combination with ertugliflozin will compete with combination products from rivals, including Eli Lilly’s Glyxambi, which combines Jardiance with its DPP-4 treatment Tradjenta.

Jardiance, in a large study, demonstrated its ability to significantly cut the risk of heart-related deaths and hospitalizations from heart failure, claims now included in its label. Invokana has demonstrated similar heart protective qualities in high risk patients.

Analysts are forecasting eventual annual sales exceeding $1 billion for Steglatro, but Merck and Pfizer will likely need to show similar heart protections if their medicine is to be competitive. Results of AstraZeneca’s heart safety trial of Farxiga are expected in 2019.

Diabetes, characterized by elevated blood sugar levels, affects roughly 30 million Americans, and can lead to severe damage to a range of organs in the body, including the eyes and kidneys and significantly increases the risk of heart attack and stroke.