Diabetes company DexCom (DXCM 0.46%) has been an incredible investment over the past decade. Its 2,500% returns during that time have dwarfed the S&P 500 and its 177% gains. And despite those impressive results, DexCom is still growing and likely will continue to expand for years as diabetes becomes more prevalent in society.

The only downside is the stock itself isn't cheap, trading at more than 186 times its trailing profits. Is DexCom's stock too expensive, or is this an investment that still has enough runway left to potentially help you become a millionaire?

Where the company is today

DexCom makes continuous glucose monitoring (CGM) devices that help people with diabetes stay on top of their glucose levels. It's a more convenient way of managing diabetes, as it doesn't involve the use of finger-sticks. Currently, the company is in the midst of rolling out its newest CGM, the G7. It promises to have more accuracy than the G6 version, and it's also 60% smaller (it's roughly the size of three stacked quarters). That will give users more flexibility in deciding where to insert it.

The launch of the G7 could help with DexCom's growth rate, which has been declining in recent years:

DXCM Revenue (Quarterly YOY Growth) Chart.

DXCM Revenue (Quarterly YOY Growth) data by YCharts.

The bigger problem for value investors is below the top line. While the company does generate terrific growth margins of over 65%, DexCom has spent nearly as much on cost of sales as it has on selling, general, and administrative costs over the past 12 months ($906 million versus $904 million).

Research and development costs of $623 million and other expenses on top of that have resulted in the company netting a lean profit of just $168 million (on revenue of $2.7 billion) during that time frame, for a modest profit margin of 6.3%.

This year, DexCom projects that its sales will be around $2.9 billion, growing between 17% and 19% from the previous year. And down the road, there could be even more growth opportunities for the company.

Global expansion offers more growth potential

Diabetes costs are on the rise, and so there's a growing need for ongoing care and ways to more efficiently stay on top of the illness, such as using DexCom's CGMs. Diabetes cost the healthcare system $966 billion last year, and that number is only going to rise. According to the International Diabetes Federation, there will be 783 million adults living with diabetes by 2045, up from 537 million today. And the IDF estimates that more than 75% of the adults with diabetes are in low- or middle-income countries.

This is where DexCom's global expansion can play a key part in its future growth. DexCom has been expanding into other parts of the world, but international revenue accounts for just 27% of its top line today. The positive, however, is that the international segment is driving more growth (41%) this year than the U.S. market (14%). DexCom sells its products all over the world, but besides the U.S., no single country makes up more than 10% of its revenue.

Can DexCom make you a millionaire?

The sheer growth opportunities that are ahead of DexCom make this a truly unstoppable stock. Demand for DexCom's CGMs will likely only rise as diabetes cases continue to increase and as the company expands its presence around the world.

Investors shouldn't get too hung up on earnings ratios because for a company like DexCom that is still rapidly growing, overhead and operating costs will likely remain elevated until the business slows down. And when it does, as it tries to focus more on efficiency and getting rid of redundancies in its operations, profit numbers should improve, and its earnings multiples will look more reasonable.

DexCom can certainly make you a millionaire, given the potential it holds. How long it takes you to get to that milestone will depend on multiple variables, including how much you invest, how long, and what growth rate the healthcare stock averages over that time. But what appears certain is that DexCom definitely has the potential to generate some great returns for investors, even at its current price.