What happened

Shares of medical device company and diabetes specialist DexCom Inc. (NASDAQ:DXCM) slipped sharply Thursday morning, declining by more than 36% as of 11:50 a.m. EDT. This tumble stemmed from the FDA's approval of Abbott Laboratories' (NYSE:ABT) FreeStyle Libre Flash Glucose Monitoring System, which is the first continuous glucose monitoring device to not require a finger-stick blood sample for calibration. Patients using DexCom's G5 Mobile device, on the other hand, need to perform up to two finger-sticks per day for the purposes of calibration.  Abbott's shares were up by more than 4% on the back of this positive regulatory development. 

A person pricking a bubble with a money sign inside.

Image Source: Getty Images.

So what

DexCom's stock has skyrocketed in the last few years because of its dominant position in the rapidly growing glucose-monitoring market. In fact, sales of its G5 mobile CGM were forecast to grow by another 25% to 30% this year after the Centers for Medicare and Medicaid Services ruled that the device was indeed "therapeutic," and could therefore be covered under Medicare Part B. With the entry of Abbott's more user-friendly device, though, DexCom's blistering levels of growth may start to taper off. 

Now what

Can Abbott's newly approved CGM device truly disrupt the market and steal a significant chunk of the market share away from DexCom? Based on the performance of DexCom's shares Thursday, the overwhelming sentiment among investors appears to be "yes," and I happen to agree with the market's initial assessment.

Unfortunately, DexCom is about a year away from bringing a similar no-calibration (and hence, no finger-stick) device to market, and that lag could spell disaster for the CGM specialist. A first-mover advantage, after all, should translate into a formidable economic moat against follow-on devices -- putting DexCom in a bad position. So while it might be tempting to grab some shares in the wake of this dramatic decline, I'd caution against it for the time being. 

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.