Another person is added to the population of the United States every 17 seconds. Unfortunately, another American is diagnosed with diabetes every 17 seconds also.

Nearly 19 million people in the country have already been diagnosed with either type 1 or Type 2 diabetes. An estimated 7 million have diabetes that has gone undiagnosed. And a staggering 79 million Americans have prediabetes.

That's the bad news. The good news is that there are more than 200 medications in development that target diabetes or related conditions, with dozens of biopharmaceutical companies focusing on the disease. Here are three companies at the cutting edge of diabetes research.

1. Eli Lilly (LLY 3.77%)
Lilly already claims several of the leading diabetes drugs among its product lineup, including Humalog, Humulin, and Tradjenta. The big drugmaker isn't resting on its laurels, though. Lilly awaits regulatory approval for type 2 diabetes drug empagliflozin and a biosimilar version of Sanofi's Lantus that the company developed with partner Boehringer Ingelheim.

Better yet, Lilly has four other drugs in the pipeline that hold potential for success, two of which are in late-stage trials. Long-acting type 2 diabetes drug dulaglutide exhibited superior glycemic control over a couple of current leading drugs, including Januvia and Bydureon, in reducing phase 3 studies. Dulaglutide, like Bydureon, only has to be taken once per week, but Januvia must be taken daily.

While Lilly waits on approval for a Lantus biosimilar, it has another drug in the wings that could be even better. LY2605541, which is in phase 3 development, achieved greater improvement of glycemic control than Lantus in an earlier phase 2 trial. And it accomplished this with patients taking less insulin. If phase 3 goes well, Lilly could submit LY2605541 for regulatory approval as early as next year.

2. Merck (MRK -0.15%)
Like Lilly, Merck has several successful drugs on the market that treat diabetes, most notably Janumet and Januvia. Merck's pipeline includes two diabetes drugs -- omarigliptin and ertugliflozin.

Omarigliptin, also known as MK-3102, is in a late-stage study. The once-weekly pill, like Merck's blockbuster Januvia, is a DPP-4 inhibitor that lowers glucose levels in type 2 diabetes patients by reducing the glucagon hormone. 

Ertugliflozin is still in phase 2 but could emerge as a big winner for Merck in the diabetes market. The drug, which was licensed from Pfizer (PFE 0.11%) earlier this year, is an SGLT-2 inhibitor -- a relatively new class of diabetes drug that increases glucose levels by blocking reabsorption of glucose in the kidneys. Merck, which agreed to split potential future revenue with Pfizer on a 60/40 basis, plans to test ertugliflozin by itself as well as in combination with Januvia and possibly other drugs.

3. MannKind (MNKD 9.49%)
While Lilly and Merck share several common characteristics, MannKind stands out from the pack. The company is small and has no products on the market. However, its experimental diabetes drug Afrezza certainly is on the cutting edge.

Afrezza is a rapid-acting inhaled insulin that targets both type 1 and type 2 diabetes. While many focus primarily on the fact that the drug is inhaled rather than injected (and therefore more convenient to take), Afrezza's rapid-acting mechanism that closely mimics how a healthy pancreas functions could be an even greater strength.

MannKind recently completed its phase 3 studies for Afrezza. The company expects to submit the drug for regulatory approval in the U.S. soon and could go to market next year if all goes well.

More on the way
The best news of all for the millions of patients in the U.S. and across the world is that these three companies aren't alone. Even more new drugs could be on the way soon. 

Of course, not all of the drugs in clinical testing will prove to be successful. Some of the products mentioned above could encounter difficulties in gaining approval. With plenty of companies plowing ahead with diabetes research, though, new and improved treatment alternatives should be just around the corner.