Shares of Teladoc Health (TDOC -2.91%) soared 140% in 2020 as the coronavirus pandemic pushed the adoption of telehealth services into overdrive. This leading provider of medical services at a distance also became a much larger company by acquiring Livongo Health for $18.5 billion last year.

Some investors are concerned about what will happen to Teladoc Health's hot streak once COVID-19 vaccine supplies catch up with demand. While the volume of acute-care services the company facilitates will likely dip, demand for the unique chronic-care services Teladoc gained from Livongo will make up the difference.

Telemedicine visit.

Image source: Getty Images.

Why Teladoc can continue climbing in 2021

Roughly half of all American adults could use help monitoring and managing at least one chronic condition. Investors can look forward to further gains in 2021 and beyond because there really isn't a viable competitor for the type of chronic-care services Teladoc Health can provide now.

Livongo made its stock market debut in 2019, and by the end of June 2020, its service for diabetes boasted over 400,000 members. Livongo made impressive strides in a short time, but there are still more than 30 million Americans with diabetes who haven't been signed up yet. Teladoc also inherited a burgeoning service for managing high blood pressure that has around 40 million potential members in the U.S. 

When Teladoc reports fourth-quarter earnings, signs of cross-selling between the company and Livongo for diabetes could push the stock through the roof. Teladoc Health boasted around 52 million members at the end of September, and more than a fifth could use some help managing their case of diabetes.