The diabetes drug Byetta, marketed by Eli Lilly & Company and Amylin Pharmaceuticals, was linked to four more deaths in patients with pancreatitis, adding to two deaths announced by federal regulators last week.

No definite relationship between Byetta and the deaths has been proved, and the Food and Drug Administration was aware of the additional deaths when it made its announcement last week, Amylin’s chief executive, Dan Bradbury, said on Tuesday. The company is talking with the F.D.A. about adding warnings on the drug’s prescribing information.

Byetta is Amylin’s leading product.