Type 2 Diabetes and Beta-Blockers, What You Should Know
When you think about risk factors for type 2 diabetes, obesity, high blood pressure, and inactivity may come to mind. One lesser known factor is use of beta-blockers, but not all of the drugs in this class may raise the chances of developing type 2 diabetes.
Some beta-blockers increase diabetes risk
Beta-blockers (aka, beta-adrenergic blocking agents or beta antagonists) have been on the market for about six decades. The first clinically beneficial beta-blocker to enter the market was propranolol, which was prescribed to treat angina pectoris, a condition in which the heart's need for oxygen exceeds the available supply.
Since then, propranolol and other beta-blockers have been developed and prescribed most often for arrhythmias (abnormal heart rhythms), atrial fibrillation (irregular heart rhythms), high blood pressure, and heart attack, and less often for migraines, anxiety, overactive thyroid, and glaucoma. Beta-blockers work by slowing the heart beat and reducing contractions of blood vessels in the heart, brain, and throughout the body.
According to cardiologist Ragaendra R. Baliga at The Ohio State University Wexner Medical Center, "Studies show that older beta- blockers can increase a patient's risk of type 2 diabetes by more than 25 percent." While raising the risk of diabetes is not good for anyone, it is especially damaging for individuals who already have conditions that affect the heart and vascular system.
In a recent issue of Heart Failure Clinics, Baliga explained that "older beta-blockers are doubled-edged swords. They save lives, but you want to avoid complications down the road, like diabetes." When some beta-blockers are used for a long time, they may have a negative impact on insulin sensitivity and lipid profiles, as well as cause weight gain, all risk factors for diabetes.
Among the older beta-blockers are atenolol (Tenormin), metoprolol (Lopressor), and propranolol (Inderal LA). Baliga noted that when patients have no other limitations, he considers prescribing newer beta-blockers, such as carvedilol (Coreg), rather than the older drugs. Recent research has suggested carvedilol may improve the efficiency of insulin and thus help prevent diabetes.
Not all research has shown an increased risk of diabetes associated with older beta-blockers, however. A 2011 study from Tulane University explored the risk of new-onset diabetes among individuals with high blood pressure who were starting therapy with carvedilol or other beta-blockers (i.e., atenolol, metoprolol).
Among the 3,084 patients who took carvedilol and the 9,252 who took the other beta-blockers, the rate of new-onset diabetes during the mean follow-up period of 12.8 and 14.8 months, respectively, was 3.16 per 100 person-years in the carvedilol group and 3.36 in the other beta-blocker group.
Therefore, the authors concluded that the risk of new-onset type 2 diabetes among patients with high blood pressure was similar between the newer beta-blocker (carvedilol) and older beta-blockers.
The bottom line
The new report indicates there may be an increased risk of type 2 diabetes among people who take the older beta-blockers on the market. However, Baliga emphasized that anyone who is taking beta-blockers should not stop or switch their medication without first consulting their healthcare provider about the potential for type 2 diabetes and which medications may be more appropriate.
Baliga RR et al. β-Blockers in heart failure: breaking tradition to avoid diabetes?Heart Failure Clinics 2012 Oct. 8(4): xiii-xvi
Fonseca V et al. Risk of new-onset diabetes mellitus associated with beta-blocker treatment for hypertension. Current Medical Research and Opinion 2011 Apr; 27(4): 799-807
Kveiborg B et al. Metoprolol compared to carvedilol deteriorates insulin-stimulated endothelial function in patients with type 2 diabetes--a randomized study. Cardiovascular Diabetology 2010 May 25; 9:21