A beta-blocker blood pressure medicine proved significantly better in keeping blood sugar levels from rising in diabetics than another widely used member of the beta-blocker family, according to results of a large clinical trial.

The study involved 1,235 high-risk patients with type 2 diabetes and hypertension - two of the biggest risk factors for heart disease. It measured long-term blood sugar levels of those taking Glaxo’s Coreg, or carvedilol, against those taking the generic drug metoprolol for at least five months.

Most of those in the study were also taking cholesterol medication.

While both drugs were similarly effective in lowering blood pressure to the desired goal of less than 130 over 80, the study presented on Tuesday at the American Heart Association annual scientific meeting demonstrated Coreg’s superiority in keeping blood sugar levels from worsening.

“Side effects are the big Achilles heel of beta-blockers,” said Dr. George Bakris, director of the hypertension clinical research unit at Rush University Medical Center in Chicago and the lead investigator of the study.

Beta-blockers generally do a good job of lowering blood pressure and decreasing some cardiovascular risks, Bakris said. But they tend to raise blood sugar, slow the heart rate and can increase cholesterol problems such as triglycerides.

Slow heart rate, for example, was much higher in the metoprolol group, Bakris said.

At least 18 million Americans suffer from high blood pressure, type 2 diabetes and High cholesterol, Bakris said, making traditional beta-blockers that raise blood sugar problematic for this patient population.

The average age of patients in the trial was 61, with about 42 percent female and 13 percent African-American.

Coreg has been on the market since 1997 as a treatment for hypertension and heart failure with sales of $577 million for the first nine months of this year.

Researchers believes the antioxidant activity of Coreg is what separates it from other beta blockers.

This study should help allay concerns of prescribing it for millions of diabetics, Bakris said.

“This gets you to where you need to be as far as blood pressure goes without the extra baggage of worrying about those other cardiovascular risk factors getting worse,” he said.