Amylin Pharmaceuticals Inc., a San Diego company focused on treating diabetes, posted a narrower-than-expected loss for the third quarter and announced that its injection drug Byetta won the Food and Drug Administration’s approval for a new use.

The company’s quarterly loss fell to $13.2 million, or 9 cents per share, from $50.7 million loss, or 35 cents, in the same period last year. Meanwhile, revenue rose 12 percent to $175 million — including a $15 million milestone payment from Eli Lilly and Co. in connection with the European launch of its Bydureon injection drug for people with type 2 diabetes.

Analysts were expecting a wider loss of 15 cents a share on revenue of $166 million, according to Thomson Reuters.

“We continue to advance our goal of bringing the first ever once-weekly diabetes therapy to patients in the U.S.,” Amylin President and CEO Daniel M. Bradbury said in reference to Bydureon in an Oct. 19 statement. “We are closely monitoring Bydureon launches across Europe and will apply insights from those launches to our U.S. planning for this important therapy.”

The drug is “well positioned” for an early 2012 domestic launch, the company said.

Separately, Amylin and partner Eli Lilly said on Oct. 19 that the FDA has approved a new use for the drug Byetta, which stimulates the body’s ability to produce insulin and also has been shown to reduce appetite. Byetta can now be used as an add-on therapy with insulin glargine to improve blood sugar control “without weight gain or an increased risk of hypoglycemia,” said John Buse, director of the Diabetes Care Center and chief of the Division of Endocrinology at the University of North Carolina School of Medicine in Chapel Hill, N.C.

In the wake of the FDA news, Amylin shares, which trade on Nasdaq under the symbol AMLN, rose 15 percent on Oct. 20, reaching a high of $11.80. Shares were trading at $11.61 on the afternoon of Oct. 21.