Lipitor (sold generically as atorvastatin) belongs to a popular class of cholesterol-lowering drugs called statins, which make up a major portion of all prescriptions filled in the United States each year. Lipitor plays a role in that popularity: It was the top-selling prescription drug in 2011, generated $7.7 billion dollars in U.S. sales for manufacturer Pfizer, Inc., that year. It remains one of the most widely prescribed drugs on the market.
Like all statins, Lipitor helps prevent heart disease and stroke by lowering the level of cholesterol in the blood. Recently, however, medical researchers uncovered new risks associated with the drug, including an increased risk for type 2 diabetes.
In 2012, the U.S. Food and Drug Administration (FDA) updated the safety labels for all statins and warned consumers that the drugs may be linked to diabetes. Other studies suggest the risk may be even higher for older women. The FDA’s label revisions also indicated that Lipitor and other statins can cause damage to the livers, muscles and cognitive function of some patients, though reports of these injuries are rare.
How Does Lipitor Cause Diabetes?
Although clinical research on Lipitor and other statins indicates these drugs can increase a patient’s risk for developing diabetes, they shed little light on how the increased risk occurs. Type 2 diabetes occurs when the body fails to properly use or produce insulin, a crucial hormone the body uses to convert food into energy.
Bodies break down the food we eat into sugar, or glucose, which travels throughout the bloodstream. But if insulin isn’t working the way it should, glucose can’t enter the body’s cells to provide them with the energy they need. This causes a spike in blood sugar levels – a problem that can result in serious health complications.
Researchers suspect that taking statins, including Lipitor, impairs the function of special cells in the pancreas that store and release insulin. There is also evidence that statins can decrease the body’s sensitivity to insulin.
Women and Lipitor Diabetes Risk
|Who is Most at Risk for Diabetes from Statin Use?|
|Lipitor and Crestor users||Post-menopausal women|
|Asian and white women||Women with a healthy BMI (non-obese)|
One 2012 study published in the Archives of Internal Medicine showed that post-menopausal women who took Lipitor or other statins faced a 48 percent increased risk for developing type 2 diabetes compared to those who did not.
The study, which included 153,840 non-diabetic women between the ages of 50 and 79, considered several other factors also known to increase the risk for diabetes, including advanced age, obesity and lack of physical activity.
Researchers found that the risk for diabetes from statins varied among ethnicities. Asian women carried the highest risk followed by white women and Latinas. African American women experienced the lowest risk. The body mass index (BMI) of the patients also affected diabetes risk. Women with a healthy BMI faced a higher risk than obsess women, who have a BMI higher than 30.
Because women are less likely to suffer a heart attack than men, their statin use is lower historically. That trend changed in recent years. According to the Centers for Disease Control, 36 percent of women between the ages of 64 and 74 and 39 percent of those 75 and older take statins to prevent their first heart attack or a repeat cardiac event. For those age ranges, nearly 50 percent of men are taking statins.
Clinical Studies on Statins and Diabetes Risk
Controversy about a possible link between statin use and diabetes risk intrigued researchers for more than a decade. Scottish researchers published the first study evaluating the connection, the West of Scotland Coronary Prevention Study (WOSCOPS), in 1995.
Although WOSCOPS returned promising results in terms of diabetes risk, the study only analyzed one statin, Pravachol (pravastatin), which a 2001 study later found to reduce diabetes risk by as much as 30 percent. This favorable effect, however, turned out to be unique to Pravachol. Researchers have discovered no evidence of a reduced diabetes risk with Lipitor or any other statin.
In a 2009 meta-analysis published by the American Diabetes Association, researchers reviewed WOSCOPS and five additional clinical trials that investigate diabetes risk from statin use. Excluding the results from WOSCOPS, statin use was associated with an 11.5 percent increased risk for diabetes. The additional studies included data on patients taking Lipitor, Crestor (rosuvastatin) and Zocor (simvastatin).
More recently, in a study published May 2013, Canadian researchers investigated the diabetes risk of six statins: Pravachol, Lipitor, Crestor, Zocor, Lescol (fluvastatin) and Mevacor (lovastatin). Compared to Pravachol, which was used as a control for its favorable effects on diabetes, the other statins were found to increase diabetes risk by 10 to 22 percent. The highest risk for diabetes was associated with Lipitor (22 percent) and Crestor (18 percent). Both drugs are routinely prescribed in higher potencies than other statins. There is some evidence that the diabetes risk increases with dosage.
While doctors don’t know how statins cause diabetes, research has raised some serious concerns. For some patients, the risk for diabetes and other potential side effects may outweigh the overall benefits statin therapy can provide.
Lipitor can certainly provide life-saving benefits to people at high risk for suffering a repeat heart attack, but a vast majority of statin users take the drugs to prevent a first heart attack, despite no history of heart disease. Although medical experts do not recommend that anyone stop taking Lipitor because of potential statin side effects, patients are encouraged to meet with their doctors to weigh the benefits of statin therapy against the risks for each unique situation.