The Food and Drug Administration has approved a new injectable diabetes drug from Eli Lilly and Co. for adults with the most common form of the disease.

The agency on Thursday cleared the drug, Trulicity, as a weekly injection to improve blood sugar control in patients with type 2 diabetes, which affects more than 26 million Americans.

Type 2 diabetes accounts for 90 percent of U.S. cases of the disease and occurs when the body doesn’t properly produce or use the hormone insulin. Drugs to treat the disease represent a large slice of Lilly’s product portfolio, which includes the insulins Humalog and Humulin.

Indianapolis-based Lilly is counting on new drugs like Trulicity to replace falling revenue from blockbusters like the antidepressant Cymbalta, which is facing cheaper generic competition.