Although many stocks are trading at or near their 52-week highs right now, that doesn't mean that they will run out of steam or that they are due for a crash. By focusing on long-term growth opportunities involving healthcare, e-commerce, and technology, investors won't need to worry about short-term price movements or earnings performances alone.

DexCom (NASDAQ:DXCM)FedEx (NYSE:FDX), and Adobe (NASDAQ:ADBE) may not be terribly cheap picks today, but they could still make for solid long-term investments that you can buy and hold for years.

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1. DexCom

Medical device company DexCom makes life a little bit easier for people living with diabetes. Its G6 continuous glucose monitoring (CGM) system sends users real-time glucose readings. It doesn't require finger sticks, either. With convenience and ease of use in mind, the CGM has quickly become the company's flagship product. Earlier this year, DexCom partnered with Teladoc Health (NYSE:TDOC) to help provide users of its platform with reports and information to help manage their blood glucose levels, at no additional cost. 

Telehealth is a great way to integrate data from DexCom's devices, and it could open up a new avenue for the company to accelerate its growth. For proof of that, you only need to look at Teladoc's impressive numbers. In 2020, the company reported 10.6 million total visits, which was a year-over-year increase of 156% as more people opted for virtual physician visits over in-person ones due to the pandemic. But in addition to telehealth, there's a significant need for better diabetes management in general. The Centers for Disease Control and Prevention previously forecasted that by 2050, one in three U.S. adults could have diabetes, up from just one in 10 in 2010. And diabetes isn't a disease patients can simply stop treating.

DexCom's business has proven resilient amid the public health crisis. The company reported sales of $1.9 billion in 2020, up 31% from the previous year. And in 2021, it expects its top line to continue to grow by up to 20%. For patients with a chronic disease like diabetes, the ongoing need for care ensures that there will be plenty of demand for DexCom's products for the foreseeable future.

In the past 12 months, the healthcare stock has risen 37% and has underperformed the S&P 500 and its 50% gains. But over the long term, that isn't a trend that I would expect to continue as there are too many growth opportunities for DexCom to slow down its ascent. That is also why I wouldn't worry about the stock's hefty price-to-earnings (P/E) multiple of 77, which is well above the 27 times earnings the average stock in the Health Care Select Sector SPDR Fund trades at. With long-term growth in mind, DexCom is a great buy and investors shouldn't be too bothered with how the company has performed over just the past four quarters.

2. FedEx

One positive consequence of the pandemic is that companies have been improving their online capabilities to better adapt to the possibility that consumers aren't able to visit their storefronts, especially amid lockdowns. And while lockdowns may be a thing of the past once the pandemic is over, that doesn't mean consumers won't be ready to give up that convenience. This makes logistics another hot sector to invest in.

A report from Allied Market Research projects that the global logistics market will be worth approximately $13 trillion by 2027, growing at a compounded annual growth rate (CAGR) of 6.5% until then. And it's hard to go wrong with a top company like FedEx to take advantage of those opportunities. For the nine-month period ending Feb. 28, FedEx's sales of $61.4 billion grew 18.4% from the previous year. Lower fuel costs and greater efficiencies have also helped Fedex's bottom line double during that time to $3.4 billion. 

Although the stock has been on a run this year, rising 140% in value, it still may not be too late to invest in the business. As companies like AmazonShopify, and Etsy rise in popularity and generate more revenue on their platforms, that is only going to fuel more growth for logistics and timely shipping. In 2020, online spending in the U.S. rose 44% from the previous year -- the highest annual growth rate in decades. And as e-commerce grows, so too will the demand for logistics. Although Fedex's stock isn't dirt cheap, at a P/E multiple of 25, it is still lower than the 29 times earnings the average stock in the SPDR S&P 500 ETF Trust trades at.

3. Adobe

On March 23, Adobe released its first-quarter results for fiscal 2021 where sales for the period ending March 5 were a record $3.9 billion and grew an impressive 26.3% year over year. What I love about Adobe is that the bulk of its business is subscription-based and recurring. During the past quarter, 91.8% of sales came from subscription revenue. That's even higher than the 88.4% it accounted for a year ago.

The global software as a service (SaaS) market is rising rapidly, and analysts from KBV research project that it will be worth $185.8 billion by 2024, rising at a CAGR of 21.4% until then. With a popular and versatile suite of products, including Photoshop and Publisher, there's little reason to doubt that Adobe won't be able to tap into that growth as its software is essential for many industry professionals.

Strong growth prospects, accompanied by impressive gross margins that typically come in at 85% or better, put Adobe in a fantastic position to continue generating great results for a long time. In 12 months, shares of this tech stock have risen by 58%. Today, the stock trades at 44 times earnings, which is well above the S&P 500 average. However, you shouldn't expect to catch it at much of a discount anytime soon, as its business looks to be as strong as ever.

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.