A new type of diabetes drug that helps the body control blood sugar won U.S. Food and Drug Administration approval, the agency said on Tuesday.

Merck & Co. Inc.‘s oral diabetes drug Januvia, generically known as sitagliptin, is the first in a new class of drugs that aims to treat the disease with fewer side effects.

The FDA approved the once-a-day drug to treat type 2 diabetes, which affects the majority of the nearly 21 million Americans with the disease.

It occurs when the body builds resistance to insulin needed to break down food and causes blood sugar levels to be too high. Obesity is a major risk factor.

Merck said the price of the tablet will be $4.86 per day.

Januvia, known generically as sitagliptin, is expected to face competition from Novartis AG’s rival drug Galvus, which is awaiting FDA approval possibly next month.

Both drugs are part of a new class of drugs called dipeptidyl peptidase IV, or DPP-4, inhibitors that work to enhance the body’s own ability to lower blood sugar. In clinical trials of the new class of drugs, patients did not gain weight.

“For millions of Americans with type 2 diabetes, who continue to have inadequate blood sugar control, the approval of Januvia marks an important advance in the fight against diabetes,” said Dr. Steven Galson, director of the FDA’s Center for Drug Evaluation and Research.

“We now have another option that treats the disease in an entirely new way that can be added to existing treatment regimens to help patients gain more control over their blood sugar levels,” he said in a statement.

Januvia and Galvus will compete with older diabetes medications known as thiazolidinediones, or TZDs, used to make patients less resistant to insulin. Those drugs are used as add-on treatments and have been linked to water retention and weight gain.