U.S. health regulators approved a new combination therapy for type 2 diabetes from Merck & Co, the first to combine a diabetes drug with cholesterol-lowering medicine in one tablet.

Merck's new drug Juvisync combines the drugmaker's diabetes medicine Januvia, which helps lower high blood sugar levels, with simvastatin, a commonly prescribed statin that helps lower cholesterol alongside diet and exercise.

About 20 million Americans have type 2 diabetes, and many of them also have high cholesterol levels. The conditions can lead to increased risk of heart disease, stroke, kidney disease and blindness, especially if left untreated or poorly treated, the Food and Drug Association said.

For Merck, this is a chance to boost sales of Januvia, generically known as sitagliptin, whose sales rose 30 percent to $779 million in the second quarter.

The American Diabetes Association guidelines recommend statin therapy for anyone who has both diabetes and cardiovascular disease, regardless of cholesterol levels. They also recommend statins for anyone older than 40 with diabetes and with cardiovascular disease risk factors, such as high blood pressure.

Merck's experts have estimated that 6 million to 8 million of the type 2 diabetics who should be on a statin have not been receiving that therapy -- a gap that the company hopes to fill with the single-tablet Juvisync.

"Although clinical guidelines put people with diabetes at the same risk level as those with coronary heart disease, nearly 40 percent of eligible patients do not receive statin treatment," Dr. Barry Goldstein, Merck's vice president for diabetes and endocrinology, said in a statement. "We are proud to bring forward a treatment option that can help address this important health issue."

The FDA on Friday approved the combination in several dosage strengths.

The most common side effects of Juvisync include upper respiratory infection, stuffy or runny nose and sore throat, headache, muscle and stomach pain, constipation and nausea, regulators said.

Merck will now have to conduct a post-marketing clinical trial to compare how Januvia lowers glucose alone compared to its combination with simvastatin, the FDA said.

Merck's shares were up 1.5 percent at $31.88 in afternoon trading on the New York Stock Exchange.

Approved in 2006, Januvia was the first FDA-backed member of a new class of drugs called DPP-4 inhibitors that enhance the body's ability to lower elevated blood sugar. It has previously been coupled with another diabetes drug, metformin, and sold under the brand name Janumet. Merck's second-quarter sales of Janumet reached $321 million.