Eli Lilly Thursday posted better-than-expected first quarter revenue and profit, although sales of its popular weight-loss drug, Zepbound, came in slightly below Wall Street estimates, sending its shares down 2% in premarket trading.

The success of the company's diabetes and weight loss treatments has led Eli Lilly to become the world's most valuable healthcare company, worth more than $800 billion.

It competes with Danish drugmaker Novo Nordisk in the lucrative market for these treatments, known as GLP-1 agonists.

Zepbound posted sales of $2.31 billion for the latest quarter. Analysts were expecting sales of $2.33 billion, according to LSEG data.

On an adjusted basis, the U.S. drugmaker earned $3.34 per share for the quarter, compared with analysts' estimates of $3.02 per share.

Total revenue was $12.73 billion for the quarter ended March 31, compared with expectations of $12.67 billion.