What happened

Shares of Senseonics Holdings (SENS 3.43%) skyrocketed 340% in the first half of 2021. The stock vaulted more than 500% higher by mid-February, but gave up some of those gains.

One key early catalyst for Senseonics was a positive coverage decision in January by health insurer EmblemHealth for the Eversense continuous glucose-monitoring (CGM) system used by individuals with diabetes. That was just the beginning of the good news for the company, though.

In June, Senseonics reported positive results from a clinical study of its version of the Eversense device that can remain implanted for 180 days. The company's current version of the CGM system marketed in the U.S. can be used for up to 90 days.

It also didn't hurt that Senseonics became a favorite of the Reddit investing community along the way. The now well-known WallStreetsBets subreddit played up the company's opportunities, as well as its possibility as a short-squeeze candidate.

Physician wearing a white coat with a marker writing the word "diabetes."

Image source: Getty Images.

So what

Probably the most important of the positive catalysts thus far this year for Senseonics is its clinical results for the 180-day version of Eversense. This version of the CGM device is already available in Europe. Not coincidentally, most of Senseonics' revenue in the first quarter came from Europe.

Senseonics hopes that it will win an OK from the Food and Drug Administration (FDA) to launch the 180-day version of Eversense in the U.S. market. The company has lined up Ascensia Diabetes Care as a partner to help commercialize the device. 

Now what

The main thing to watch with Senseonics is its progress toward launching the 180-day Eversense CGM system in the U.S. Investors should keep their eyes open for a potential short squeeze, as well. As of June 30, 2021, nearly 21% of Senseonics' outstanding shares were sold short.