You may notice DexCom, Inc. (DXCM) - Get DexCom, Inc. Report on your list of biggest losers for the stock market on Thursday. Shares are being hammered, down about 36% to new 52-week lows on the entrance of Abbott Labs (ABT) - Get Abbott Laboratories Report into one of its key markets.

In fact, DexCom stock is hitting its lowest levels since late-2014 on the news. "This is a real shot" by Abbott, TheStreet's Jim Cramer said on CNBC's "Stop Trading" segment.

So what's happening? The FDA has approved Abbott's FreeStyle Libre Flash Glucose Monitoring System. In fact, it's the first blood glucose monitoring system that doesn't require patients to prick their finger. The device is worn on the back of patients' upper arm and can continuously monitor glucose levels for 10 days.

There's good characteristics to the new device, and investors are realizing just how competitive it can be against DexCom's offering, Cramer reasoned. The differing sizes of the companies doesn't help. Abbott's $94 billion market cap dwarfs the now sub-$4 billion market cap of DexCom.

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In other words, Abbott has far more flexibility, resources and marketing power behind the new device, which could really put the pressure on DexCom. MediCare and the FDA are really going to like the new device, said Cramer, who also manages the Action Alerts PLUS charitable trust portfolio.

"I think that Abbott is a buy, even up here," Cramer concluded. Ironically, Abbott Labs is up 3.6% and hitting new 52-week highs in Thursday's session, now up 41% on the year.

Abbott is a holding in Jim Cramer'sAction Alerts PLUS Charitable Trust Portfolio. Want to be alerted before Cramer buys or sells ABT?Learn more now.

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At the time of publication, Jim Cramer's Action Alerts PLUS had a position in ABT.