Head-to-head clinical trials can be a risky bet. If a drugmaker's product can't beat its competition, the trial becomes an advertisement for the adversary. But when the market is crowded like it is with diabetes drugs, Amylin Pharmaceuticals (NASDAQ:AMLN) didn't have much of a choice.

Fortunately it seems to have worked out for Amylin. The press release was light on details, but its once-weekly Byetta seems to have beaten Merck's (NYSE:MRK) Januvia and Takeda's Actos in a head-to-head trial in patients who were also taking metformin, the long-genericized version of Bristol-Myers Squibb's (NYSE:BMY) Glucophage. Once-weekly Byetta was able to lower A1C levels, a long-term measure of blood sugar, by 1.7 percentage points compared to 1.0 points for Januvia and 1.4 points for Actos. Assuming the patients in all three arms of the study started at the same average level, that's a nice statistically significant improvement in blood sugar levels.

The diabetics taking once-weekly Byetta also experienced greater weight loss than those on Januvia and Actos; the Actos patients actually gained weight over the course of the six-month trial. Considering about 90% of type 2 diabetics are overweight or obese, weight loss is certainly a nice side benefit of the drug.

Amylin and its marketing partner Eli Lilly (NYSE:LLY) currently sell a twice-daily version of Byetta, but because the drug has to be injected, it really hasn't caught on with patients; sales last year were less than $680 million, less than half the sales of the $1.4 billion blockbuster Januvia, which is taken orally.

The once-weekly injection regimen, made possible by Alkermes' (NASDAQ:ALKS) extended-release technology, will help sales, but these head-to-head comparisons should be the kicker that propels the drug out of its funk. Next up is a comparison against sanofi-aventis' (NYSE:SNY) Lantus and another trial comparing the once-weekly drug against metformin, Januvia, and Actos as monotherapies.

In addition to helping with marketing, all this strong data should help the drug get past the Food and Drug Administration. The company expects to submit its marketing application by the end of next quarter.

Get that blood sugar under control, go have a banana, and read this Foolishness:

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Fool contributor Brian Orelli, Ph.D., doesn't own shares of any company mentioned in this article. The Fool has a disclosure policy.