Shares of fitness tracker Fitbit Inc. FIT, -0.93% surged almost 10% in early trade Thursday, after the company said it is working with Dexcom Inc. DXCM, +0.80% to help people manage diabetes. Dexcom makes products to allow for continuous glucose monitoring and Fitibit is aiming to develop ways for diabetes patients to get a reading on their glucose levels on their wrist, without needing a smart phone or an app. "The strength of our brand and our ability to track critical health metrics continuously for up to 4+ days1, coupled with Dexcom's market leadership in CGM, present a powerful combination that we hope will help millions of people better manage their diabetes," said James Park, CEO of Fitbit. Fitbit shares are down 11.5% in 2017, while the S&P 500 SPX, -1.11% has gained 10%.