Going into 2023, Novo Nordisk's (NVO -1.70%) share price had jumped by at least 50% seven times over the previous four decades. The Danish drugmaker added one to that total last year, though, with its stock soaring 53% higher.

It probably will come as no surprise that Novo Nordisk's wildly popular drug Ozempic played a key role in the sizzling gains achieved in 2023. However, Novo's success wasn't only due to Ozempic.

Exactly how Novo Nordisk crushed it last year

Novo Nordisk got off to a strong start last year with its 2022 full-year results announced in early February. Total revenue jumped 26% year over year.

Ozempic was a big winner, with its sales vaulting 77% higher. However, another diabetes drug -- Rybelsus -- ranked as an even bigger winner, with sales soaring 134% year over year. But Novo's biggest gainer of all was weight-loss drug Wegovy. It's important to note, though, that Ozempic, Rybelsus, and Wegovy have the same active ingredient (semaglutide).

More good news for semaglutide came in March. Novo Nordisk reported positive results from a phase 3 clinical study evaluating a once-daily oral version of the drug in treating type 2 diabetes.

By April, things were going so well for the big drugmaker that it boosted its sales and operating profit guidance for full-year 2023. Novo Nordisk stated that the improved outlook stemmed partially from greater expectations for Ozempic. However, the primary factor behind the rosier forecast was impressive prescription trends for Wegovy.

It was the same song with a different verse in May. Novo Nordisk announced positive results from a late-stage clinical study evaluating oral semaglutide in helping patients lose weight.

Investors who thought it couldn't get any better for Novo Nordisk had a pleasant surprise: The company revealed in August that a 2.4-milligram dose of semaglutide reduced the risk of major adverse cardiovascular events by 20% in adults who were overweight or obese.

By that point, investors were accustomed to receiving great quarterly updates from Novo. And they weren't disappointed. The company posted strong growth for the first six months of 2023 in August. Wegovey led the way again, with sales skyrocketing 367% year over year.

In September, Novo Nordisk conducted a two-for-one stock split, making its rapidly rising shares even more affordable. The drugmaker followed up in October with another upward revision to its full-year outlook. It also announced that it was stopping a kidney outcomes trial for semaglutide. No, the news wasn't negative: Novo halted the trial because the interim analysis showed such strong efficacy, there wasn't a need to continue.

Is Novo Nordisk stock a good pick to buy now?

Novo Nordisk may be able to keep the momentum going. However, I don't think the stock is as great of a choice for investors now as it has been in the past.

My biggest concern is the threat that Eli Lilly's Mounjaro and Zepbound present to Ozempic and Wegovy. There have already been early signs this year that Lilly's drugs are eating into Novo Nordisk's market share.

Novo Nordisk isn't a horrible pick. Sales for Ozempic and Wegovy will almost certainly continue to rise. Novo's pipeline also looks promising. But investors can find better alternatives after the stock's huge gains last year, in my view.