What do you do when you're waiting to respond to your second FDA rejection, but a major scientific meeting in your field comes up? Present data from random studies, of course.

At the American Diabetes Association meeting, MannKind (Nasdaq: MNKD) reported data from a study showing that diabetics liked its inhaled insulin product, Afrezza, better than Eli Lilly's (NYSE: LLY) Humalog, which has to be injected. Both groups still had to take a long-acting insulin -- Sanofi's (NYSE: SNY) Lantus -- so patients didn't avoid injections entirely. But at least mealtime insulin didn't require a jab in the arm.

I don't know whether the diabetics who entered the study knew there was a 50/50 chance they'd get Afrezza, but if they did, the study is somewhat of a straw poll. Is it all that surprising that people with a predisposition to wanting to try inhaled insulin might actually like it?

The second presentation wasn't quite as useless. Pooled data from nine phase 2/3 clinical trials showed that taking Afrezza didn't increase the risk of cardiovascular events -- heart attacks and the like -- compared to standard injected therapies. In a post-GlaxoSmithKline's (NYSE: GSK) Avandia world, long-term heart data is always a plus, but it's not what's holding up the FDA approval either.

We probably shouldn't pick on just MannKind. VIVUS (Nasdaq: VVUS) presented data at ADA about Qnexa, but nothing in the presentations would seem to address the FDA's concerns about its obesity drug. Amylin Pharmaceuticals (Nasdaq: AMLN), Lilly, and Alkermes (Nasdaq: ALKS) presented data on Bydureon's effect on QT intervals -- what tripped up the approval -- but it wasn't the ongoing thorough study required for approval.

I'm not actually against these companies presenting relatively unimportant data at scientific meetings. They serve their purpose of keeping the drugs in front of doctors while the companies wait to sort out their issues with the FDA.

But investors need to realize their purpose and make sure they don't jump at every press release.

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Fool contributor Brian Orelli holds no position in any company mentioned. Click here to see his holdings and a short bio. 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 may not 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.