The beta-blocker blood pressure medicine Coreg proved significantly better in keeping blood sugar levels from rising in diabetics than metaprolol, another widely used member of the beta-blocker family. 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, Coreg demonstrated 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.
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.
In the GEMINI trial, important results were observed, including:
* Blood Pressure: Patients on Coreg reached protocol specified blood pressure goals at a mean daily dose that is within the range that is commonly prescribed (35 mg); patients receiving metoprolol tartrate required a mean daily dose of 256 mg, a dose not routinely prescribed, to reach protocol specified blood pressure goals.
* Diabetes control: In patients already receiving antidiabetic therapies, HbA1c was not negatively affected in patients receiving Coreg while it worsened in patients receiving metoprolol tartrate. The difference between Coreg and metoprolol tartrate on HbA1c was 0.13 percent (p = 0.0039) and twice as many patients receiving metoprolol tartrate had changes of 1.0 percent or greater (p< 0.001).
— In Coreg treated patients, there was a statistically significant reduction in insulin resistance of 9.1 percent (p = 0.004); the reduction of insulin resistance of 2.0 percent for metoprolol tartrate treated patients was not statistically significant.
* Microalbuminuria: The albumin: creatinine ratio (ACR), which is a measure of microalbuminuria, was measured in all of the patients in the trial and it was reduced in the patients treated with Coreg by 16 percent (p=0.003) compared to metoprolol tartrate. At the start of the trial, 80 percent of the patients in GEMINI did not have microalbuminuria and in that group there was a 47 percent (p=0.03) risk reduction for the development of microalbuminuria in patients on Coreg versus those on metoprolol tartrate.
* Weight: Patients taking Coreg did not gain weight. Patients taking metoprolol tartrate had a weight gain of 2.6 pounds (p<0.001).
Journal of the American Medical Association (JAMA) and presented at the 2004 American Heart Association Scientific Sessions