Updated from 9:30 a.m. EDT

Novartis

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said Tuesday that combining its experimental diabetes drug Galvus with an existing medication produced a significant drop in blood-sugar levels among diabetics.

According to new clinical trial data, the combination of Galvus and the standard diabetes treatment, Actos, showed no significant weight gain and less fluid retention vs. Actos alone. The combination therapy also reduced blood-sugar levels better than Actos did by itself. Actos is sold by

Eli Lilly

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and Japan's Takeda Pharmaceuticals.

The study was one of several released in recent days by Novartis touting Galvus, which is now under review by the Food and Drug Administration. The agency could act by year-end. The announcement came at the annual scientific session of the American Diabetes Association.

Merck

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also issued several research reports at the convention for a competing drug. Januvia is also being examined by the FDA, and Merck could hear from the agency in the fall. Both companies plan to file applications in the European Union this year.

Novartis and Merck are trying to be first company to start marketing a new class of treatments called dipeptidyl peptidase-4 inhibitors, or DPP-4 inhibitors. The companies are seeking approval for these drugs as once-a-day pills for people with Type 2 diabetes, which accounts for about 95% of the disease. Type 2 patients are unable to produce enough insulin, or their cells are unable to adequately absorb the insulin, to help this natural protein convert sugar into fuel.

The drugs try to control blood-sugar levels by affecting two cells in the pancreas, the organ that produces insulin. The drugs affect one cell that stimulates insulin production, as well as a cell that signals the liver to reduce sugar production. Actos belongs to a class of drugs nicknamed TZDs, which help muscles accept and use insulin.

Throughout late-stage clinical testing, Galvus has shown "clinically significant and consistent" reductions in blood-sugar levels as a single therapy and as part of a combination therapy involving blood-sugar control pills or injectable insulin, said Dr. James Shannon, head of development of Novartis' prescription drug unit, in a prepared statement.

The company said clinical trials show that patients taking Galvus experienced "no weight gain overall." It said side effects such as fluid retention or excessively low blood sugar were similar to a placebo in clinical studies testing Galvus as a stand-alone therapy.

The question of weight loss will be a challenge to marketers at both Merck and Novartis. Although their drugs don't cause a weight gain, they must compete against some types of drugs that produce some weight loss.

Officials from Merck, Novartis and the American Diabetes Association cautioned against making comparisons of individual companies' tests of the DPP-4 drugs because these studies don't include head-to-head comparisons.

"It's great to see patients have a choice in an area where there is a great unmet need," says Dr. Ameet Nathwani, who runs global cardiovascular and metabolism drug operations at Novartis. It's too early for doctors or patients to distinguish between the products, he says, adding that such comparisons can only be made after the FDA approves the drugs and their labels.

On Tuesday, Novartis said its Galvus-Actos combination could cut blood-sugar levels by 1.9 percentage points using a measurement known as HbA1c. The decline was achieved with the higher of two Galvus doses being tested. Actos alone caused a decline of 1.4 percentage points.

The American Diabetes Association says 7% is an acceptable level for HbA1c, and patients started the Galvus-Actos test with levels between 7.5% and 11%. The study tested 592 patients for six months who had never been treated for Type 2 diabetes. Among patients with a blood-sugar level of 9% or higher, the combination therapy produced an average drop of 2.8 percentage points.

Two-thirds of the patients taking the combination therapy achieved the 7% blood-sugar goal vs. 42.5% on Galvus alone and 42.9% on just Actos.

Meanwhile, Merck said a clinical trial of Januvia shows it had equal power in reducing blood-sugar levels but fewer side effects than a standard diabetes treatment. Merck compared Januvia with a generic drug called glipizide that stimulates the pancreas to produce more insulin.

Merck presented data for 52 weeks of an ongoing 104-week study showing thatpatients receiving a recommended once-a-day dose of Januvia achieved similar blood-sugar reductions as those taking glipizide.

However, the Januvia patients achieved an average weight loss of 3.3 pounds, while the glipizide patients gained an average of 2.4 pounds. In addition, Januvia patients had a significantly lower rate of hypoglycemia -- excessively low blood sugar -- than the glipizide patients. The Januvia rate was 4.9%, and the glipizide rate was 32%.

The company said it found "no significant safety concerns" for Januvia after analyzing 793 patients. The patients had failed to control their blood sugar while taking metformin, another standard diabetes treatment. Metformin is a member of the biguanides class of drugs, which reduce the amount of sugar made by the liver.

Merck and Novartis are trying to position their medications for their convenience as once-a-day pills and for their dual action on blood-sugar levels.

Dr. Peter Stein, senior director in metabolism clinical research for Merck, says many diabetics will use more than one drug at a time to keep their blood-sugar levels under control. "We need combination therapies," he says. "We need new options."

In other research, Merck reported no significant difference in hypoglycemia among the standard dose of Januvia, a double-strength dose of Januvia and a placebo. The research was based on the pooling of four separate studies.

There were "no clinically meaningful changes" among Januvia patients vs. placebo recipients. The most common side effects for Januvia patients were upper respiratory infections, diarrhea, joint pain, stuffy or runny nose, sore throat or urinary tract infections.