There are many ways to increase one's wealth, but one of the most reliable and accessible remains the stock market. However, getting wealthy by investing in equities takes time. That's one of the reasons it's worth holding on to shares of great companies for a while, provided that said corporations have the tools to deliver solid returns regularly.

What's more, investors can get started even with a relatively modest sum. For those with $5,000 to spare that isn't being saved for emergencies, let's consider two stocks to buy that could help grow this capital for a long time: Novo Nordisk (NVO -0.49%) and Medtronic (MDT -1.12%).

1. Novo Nordisk

Novo Nordisk is a drugmaker known for its work in the diabetes care market. For instance, it is one of the leading insulin providers in the world. The company recently made headlines in this field about a month ago after it decided to cut the prices of several insulin products by as much as 75%. These changes will go into effect in January 2024.

Novo Nordisk did so after one of its two competitors in this area, Eli Lilly, led the charge by making a similar move. How will these developments affect Novo Nordisk's long-term prospects? In 2022, Novo Nordisk's insulin products comprised almost 30% of its total sales. But the company is currently developing newer products.

Most notably, it is working on icodec, a once-weekly insulin medicine. Considering the usual daily insulin schedule diabetes patients follow, icodec should be massively successful if approved. It proved highly effective in late-stage clinical trials, and Novo Nordisk plans regulatory applications sometime this year.

So icodec should help make up for the loss in revenue from the decrease in prices for Novo Nordisk's current products. This highlights one of the most important reasons: The company is an adept innovator and has been so for a while, especially, though not exclusively, in the area of diabetes. There are 422 million patients who have this chronic illness worldwide, and the number is growing.

Novo Nordisk's expertise in this area should lead to more important therapies in the future, leading to increased revenue and earnings. Meanwhile, Novo Nordisk is also developing medicines in other areas, from Alzheimer's disease to various rare illnesses. The company is currently awaiting approval for brand-new drugs such as nedosiran, a potential treatment for primary hyperoxaluria, a condition that causes kidney and bladder stones.

Concizumab is another therapy, one for hemophilia, that could soon earn its first approval from the U.S. Food and Drug Administration. Novo Nordisk boasts well over a dozen other programs, many of which are in phase 3 studies. That paints a bright picture for the company's long-term future.

Investors would be able to acquire 15 of Novo Nordisk's shares with half of the initial capital of $5,000. Given the company's innovative abilities and focus on areas with high demand, that would be money well spent. 

2. Medtronic 

Medtronic is one of the most prominent medical device experts in the world. It operates across multiple areas, including cardiovascular health and structural heart. Medtronic routinely earns approval for dozens of new machines or adds new indications to existing ones. It has scored 150 approvals in the past 12 months alone.

Medtronic's dozens of devices are already installed and used by thousands of healthcare professionals across the U.S. and elsewhere. The company's entrenched position in this market is a significant strength since it has developed a solid reputation with the physicians who use its products. That's a good reason why many of them will continue turning to Medtronic in the future. 

One of Medtronic's most important long-term opportunities is in robotic-assisted surgery (RAS), with its Hugo system. Robot devices like the Hugo allow physicians to perform minimally invasive surgeries, which involve less cutting of a patient's skin than traditional open surgeries. The former type is typically less painful and leads to faster recoveries and less scarring, among other benefits.

The Hugo system isn't cleared in the U.S. yet, but Medtronic has been launching it in other parts of the world, including Europe and Japan. Medtronic's business is also changing, with the company in the process of splitting up its patient monitoring and respiratory interventions segment. While that will lead to less diversity, the company expects stronger revenue growth.More importantly, this move should do little to disrupt Medtronic's prospects.

Another reason to invest in Medtronic for the long haul is the company's dividend history. With 45 years of consecutive dividend increases, the healthcare giant should join the highly exclusive group of Dividend Kings in about five years.

Medtronic should continue increasing its payouts long after, along with delivering consistent revenue and earnings. With the remaining $2,500 out of that initial $5,000, investors can buy themselves 31 shares of Medtronic at current levels.