Eli Lilly and Co. will have to wait a little longer before selling a once-weekly version of its diabetes drug Byetta.

The U.S. Food and Drug Administration told Lilly and its development partners on Byetta that it wants feedback on the new product’s label, clarification of its manufacturing processes and submission of a Risk Evaluation and Mitigation Strategy.

Lilly and San Diego-based Amylin Pharmaceuticals Inc., said they will respond in the next few weeks. They plan to sell the drug under the brand name Bydureon.

But significantly, the FDA said it would require no further testing of Bydureon, which would have threatened to delay its launch much longer.

"In this scenario, we'd anticipate a second-quarter resubmission and a fourth-quarter approval," JPMorgan analyst Cory Kasimov wrote in a research note, according to Reuters.

The drug approval is key for both companies. Byetta, taken as a twice daily injection, has been successful for controlling blood sugar levels in patients and helping some lose weight. It racked up $797 million in worldwide sales last year.

But analysts expect a once-weekly injection of Bydureon to be far more attractive because of its convenience. Analysts expect sales of Bydureon to reach as high as $2 billion by 2015.

Lilly and Amylin’s chances of approval were judged high after the FDA in January approved a similar drug, Victoza, a once-daily injection made by Denmark-based Novo Nordisk A/S.

Bydureon uses technology from Massachusetts-based Alkermes Inc. to release the compound exenatide at a controlled rate.