An experimental Novartis AG diabetes drug significantly reduced blood sugar for a prolonged period during a mid-stage clinical trial, the company reported on Sunday.

Diabetics often suffer from dangerously high blood-sugar levels, which can eventually lead to heart disease, blindness and amputations if not treated effectively.

The oral drug, the first in a new class and which analysts have said could be a blockbuster, raises the level of a compound in the body called glucagon-like peptide, or GLP-1, which helps boost the level of insulin in the body.

Diabetics often suffer from dangerously high blood-sugar levels because they are unable to produce enough insulin or can’t process their insulin properly.

In a one-year, phase II trial of 71 patients, the Novartis drug was used in combination with the standard drug metformin, which makes the body’s existing stores of insulin more effective. The patients had type 2 diabetes - much more common than the inherited type 1 form - that typically begins in adulthood but is increasingly common among children.

The combination therapy lowered levels of hemoglobin A1c - a measure of long-term blood sugar control - by 1.1 percent more than did metformin alone.

Average levels of hemoglobin A1c between about 4 percent and 6 percent are considered normal, so getting a patient to 6.4 percent from 7.5 percent, for instance, can be very beneficial.

The results are considered statistically significant.

“What makes these results striking is that the patients in this study were chosen because they were being managed on what were essentially maximum doses of metformin,” said Dr. Thomas Hughes, who is in charge of diabetes research at Novartis.

“But these patients were not in control of their diabetes at the beginning of the study, they were not reaching their targets. With metformin alone, their glycemic control continued to deteriorate over the course of the year.”

By contrast, the group on the Novartis drug, LAF237, plus metformin showed a steady reduction for about 12 weeks and glucose levels didn’t rebound and rise again for the remainder of the 52-weeks of treatment, Hughes said.

Hughes said boosting GLP-1 also appears over time to help the functioning of “beta cells,” which manufacture insulin.

Patients on the combination reported a slightly higher amount of side effects, with about 69 percent of patients on the combination experiencing at least one adverse event compared with 58.6 percent of patients on metformin alone.

But the company estimated that a slightly lower percentage of patients on the combo therapy had adverse effects that were related to the drugs than metformin alone.

The only potentially serious side effect for patients on the combination would have been hypoglycemia, or low blood sugar, but the few patients who showed signs of it were tested and found not to have the condition.

Novartis is starting phase III clinical trials and intends to submit marketing applications to U.S. and European regulators in 2006.

Hughes said he is unsure whether Novartis will seek to market LAF237 as a first-line monotherapy - which could enhance its commercial potential - or as a combination treatment for patients who are failing to respond to metformin.

“It will depend on the overall results of the data that is collected in phase III,” said Dr. Michelle Baron, a Novartis researcher helping to lead the company’s clinical trials.

She said phase III trials will test LAF237 both as a monotherapy and in combination with other diabetes drugs.

The drug increases levels of GLP-1 by inhibiting an enzyme called DPP4, which Merck & Co Inc., Bristol-Myers and other companies are also targeting with their own experimental drugs. Novartis and Merck have the lead.

In fact, Hughes helped discover the target and the drug about a decade ago. “This is my baby,” he said. “No one will ever tell you that their baby is ugly or that it isn’t the brightest one in the class.”