Over the past few weeks I've been doing a deep-dive series exploring the history and future prospects of MannKind Corp. (MNKD 0.15%). Now that we know the company far better, it's time to ask the ultimate question: Is MannKind a buy?

Ever since it went public in 2004, the stock has had both bulls and bears proclaiming the merits and shortfalls of the company. Thus far, the bears have been correct about the direction of the stock, as the company has shed more than 60% of its value over the past decade, while the S&P 500 has almost doubled.

Ouch.
The opportunity in front of the company, however, remains enormous, as the Centers for Diseases Control and Prevention estimates that 29.1 million Americans suffer from diabetes, with that number reaching as high as 387 million worldwide. That number is predicted to grow rapidly, with an estimated 592 million patients expected to be diagnosed worldwide by 2035.

In pursuit of that massive opportunity, MannKind developed its first and only drug, Afrezza, an inhaled insulin that's designed to treat both type 1 and type 2 diabetes. MannKind, along with marketing partner Sanofi (SNY -0.72%), officially launched the drug for sale this past February.

Afrezza has several advantages over traditional insulin injections. Afrezza is inhaled and absorbed in the lungs, which both eliminates the need for meal time injections and allows the insulin to reach peak effectiveness faster than other insulins currently on the market. This faster action can help patients better control their blood sugar levels before and after a meal, which could make the drug very appealing to patients who currently take multiple injections ever day.

Still, huge questions remain unanswered about the drug's market potential. Will Sanofi be able to convince patients and providers that Afrezza is safe and easy to use? Will MannKind be able to hit all the milestones needed to receive the additional $775 million in payments from Sanofi? Will Afrezza wind up in the dustbin like Pfizer's earlier inhaled insulin Exubera? How will big pharma fight back against Afrezza?

We got a small glimpse of early Afrezza sales results when MannKind reported first-quarter earnings, and Wall Street didn't like the news. The company mentioned that early adoption was modest, largely due to required lung function testing prior to patients starting treatment. Management is working to overcome these obstacles, but this uncertainty has punished MannKind's stock over the past three months, as the share price fallen nearly 25% since Afrezza was launched in February.

MNKD Chart

Does the drop present a buying opportunity?
MannKind's stock is very high risk, as its near-term future is tied directly to the sales of only one very new drug. Yes, MannKind's Technosphere technology could one day find its way into many applications beyond diabetes, but those opportunities remain untapped, and the company has yet to officially announce any new partnerships.

For now, I'm personally going to stay away from MannKind's stock, as there's just too much risk at play here. Before I'd consider investing, I would want to see proof that Afrezza sales are growing rapidly, that the issues causing the delay in sales are dealt with, and that MannKind recieves one or two more royalty payments.

If those things happen, it's likely the share price will be many multiples higher than where it is now. I'm OK with that, as even if the company doubled its share price from here, the market cap would still be valued around $4 billion or so. If Afrezza really is the wonder drug we hope it will be, and the Technosphere technology platform ends up with other announced applications, there would still be plenty of upside left. But until that happens, I'm happy to sit on the sidelines and watch the story unfold.