The news coming out of this week's annual conference of the American Diabetes Association wasn't good. Global cases of diabetes doubled worldwide over the past 30 years, but in the U.S. it's even worse, with the disease increasing threefold to affect nearly 25 million Americans. If growth continues at this rate, we'll be looking at 550 million affected individuals worldwide by 2025.

Diabetes poses one of the greatest threats to our health-care system, and it therefore becomes an increasingly important target for drugmakers.

Unfortunately, the news on that front isn't even very good. Takeda's Actos, the No. 1 diabetes drug, and GlaxoSmithKline's (NYSE: GSK) Avandia have both been linked to macular edema. For Glaxo, this is just another blow for a onetime blockbuster drug that's already been tarnished with cardiac concerns. For Takeda, the latest news, combined with an FDA safety warning in mid-June that Actos may be tied to bladder cancer, could potentially put the $4.8 billion franchise in jeopardy -- if not with regulators, then from competitors' superior safety profiles.

And improving a drug's safety profile is easier said than done. Bristol-Myers Squibb (NYSE: BMY) and AstraZeneca's experimental drug dapagliflozin inhibits a specific protein and therefore works differently from Actos, but recent clinical trials identified an increased likelihood of breast and bladder cancer. Analysts don't seem to think that the news will negatively sway the FDA and that a post-approval marketing study is the likeliest outcome. Still, I've seen enough unexpected complete response letters to know how dangerous the FDA prediction game is.

For investors though, the most exciting results come from Novo Nordisk (NYSE: NVO). Its new insulin degludec showed similar efficacy to Sanofi's Lantus, but with a reduced rate of hypoglycema. Thanks to premium pricing, this could be a multibillion-dollar product for Novo. But that's not all. Perhaps more importantly, its insulin-generation booster Victoza not only cut blood sugar for those taking Eli Lilly's (NYSE: LLY) Byetta and Merck's (NYSE: MRK) Januvia, but patients also showed "significant weight loss." Victoza showed solid efficacy on this front without the troubles that seem to follow obesity drugs such as Orexigen's (Nasdaq: OREX) Contrave and Vivus' (Nasdaq: VVUS) Qnexa. One analyst put his "conservative estimate" of sales between $2 billion and $5 billion.

Diabetes treatment is going to be an increasingly important space for Big Pharma, with the potential pool of customers growing such at an alarming rate. Investors would be wise to pay attention to the space or risk the chance of missing out on the next big blockbuster.

David Williamson owns no shares of the companies mentioned. The Motley Fool owns shares of GlaxoSmithKline. Motley Fool newsletter services have recommended buying shares of GlaxoSmithKline. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.