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How concerned should statin users be about diabetes risk?

A new study linking statins to an increased risk of diabetes in women has some doctors scrambling to reassure patients that the cholesterol-lowering drugs aren’t all that risky and that they should stay on them, no matter what. But it highlights the importance of reserving these medications only for people who really need them.

“What I fear here is that people who need and will benefit from statins will be scared off of using the drugs because of reports like this,” Dr. Steven Nissen, cardiology chairman at the Cleveland Clinic, told the Associated Press. He and other leading cardiologists expressed the same dismay to me last June when a review study linked statins to increased rates of diabetes.

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That 2011 review study, though, found that the small increase in diabetes risk was outweighed by a greater reduction in the rate of heart attacks, strokes, or other cardiovascular events in those who were on statins.

The latest research, published yesterday in the Archives of Internal Medicine, didn’t look at whether statins prevented heart problems in the postmenopausal women ages 50 to 79, so it’s impossible to weigh the diabetes risk against any potential cardiovascular benefits.

What the study did find is that after three years of followup, about 4 percent of the women in the study who weren’t taking statins had developed new cases of diabetes, compared with 6.25 percent of the statin takers. After several more years of followup, nearly 10 percent of the statin users had developed diabetes compared with 6.4 percent of the older women who hadn’t taken the drugs over the course of the study.

It was, though, an observational study that simply followed those who were prescribed the drugs by their doctors, so they might have been a less healthy population to begin with. While the researchers controlled for certain factors like diet, body weight, exercise, smoking habits, and whether participants had heart disease, they wrote that they couldn’t account for all the differences between the two groups.

Perhaps one of these unaccounted for differences explains a particularly disturbing and unexpected finding of the study: Statin users with the highest risk of developing diabetes were also at the lowest end of the weight spectrum -- which goes against the notion that excess weight leads to a higher risk of developing type 2 diabetes.

“We don’t know the reason for this,” said Annie Culver, a pharmacist at the Mayo Clinic who led the study. “It could be due to some sort of confounding factor like the thinner women gaining more weight after menopause or putting on more fat around their waist, a risk factor for diabetes, during the study.”

The persistent link between statin use and diabetes underscores the importance of determining just how much those without established heart disease really benefit from taking statins. While no one disputes that statins are life-saving for patients who have had previous heart attacks, they provide much smaller benefits in those at low risk for heart disease.

As statins have become cheaper to prescribe (thanks to expiring patents that have made some available as generics) and have established a good track record for safety, more doctors have become comfortable prescribing them for prevention purposes. They might immediately prescribe a statin at the first indication of high cholesterol or even to those who don’t have high cholesterol, based solely on a blood test indicating elevated levels of inflammation.

Those sorts of practices concern Dr. Yunsheng Ma, a study co-author from the University of Massachusetts Medical School.

“Only 7 percent of the women were taking statins in our study,” which used data from as early as 1993, said Ma. Nowadays, “40 to 50 percent of older women take statins, and I think we need to know more about the risks and benefits.”

Besides the increased diabetes risk, women, in particular, are more likely to develop muscle pain from statin drugs, which happens in anywhere from 3 to 15 percent of users. Mild memory loss can occasionally occur, and in very rare cases the drugs can have a detrimental impact on the liver.

“Changes [in] diet and exercise should come first to lower cholesterol levels, and only if they don’t work should patients consider a statin,” said Ma.

Deborah Kotz can be reached at dkotz@globe.com. Follow her on Twitter @debkotz2.
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