Latest study which was published online May 23 in the journal BMJ has showed that elderly patients who take certain high-potency
cholesterol-lowering drugs especially atorvastatin, rosuvastatin and simvastatin have an increased risk of
developing diabetes relative to a lower-potency statin, pravastatin.
“Our findings are significant because statins are among the most
commonly used drugs in the world and our findings suggest that certain
statins may confer a slightly increased risk of diabetes relative to
other statins among those without a history of diabetes,” said Dr. Muhammad Mamdani, a scientist at the Li Ka Shing Knowledge Institute of St. Michael’s Hospital and senior author of the study.
Statins are prescribed not just for lowering cholesterol to prevent
cardiovascular events but also for people who have already had
cardiovascular incidents such as a heart attack, stroke or peripheral
artery disease. They are considered to be highly effective, but recent
research has linked them to an increased risk of developing Type 2
diabetes, commonly known as adult onset diabetes.
In January, Health Canada required new labelling for statins to point
out these risks, which it said were found mainly in patients with
pre-existing risk factors for diabetes such as high levels of glucose in
the blood, being obese or having high blood pressure.
Dr. Mamdani, an adjunct scientist with the Institute for Clinical
Evaluative Sciences, used the health records of 1.5 million residents in
Ontario to examine the association between statin use and new-onset
diabetes.The patients were aged 66 and over and started statin therapy
between 1997 and 2010. Atorvastatin accounted for more than half of all
new statin prescriptions followed by rosuvastatin, simvastatin,
pravastatin, lovastatin and fluvastatin. The study used
pravastatin-treated patients as the comparison group as pravastatin has
been shown to have favourable effects on diabetes in animals and in
clinical trials.
This was the largest study to date to directly compare individual
statins with respect to a risk for diabetes. The study demonstrated
significant increased risk of diabetes with some statins relative to
others irrespective of whether the patient had a prior history of
cardiovascular events.
Of the 471,250 patients they identified with no history of diabetes
and who were newly treated with a statin, patients treated with
atorvastatin were found to have a 22% increased relative risk of
new-onset diabetes compared to patients treated with pravastatin.
Rosuvastatin was linked to an 18% relative increased risk and
simvastatin a 10% relative increased risk, relative to
pravastatin. In contrast, patients treated with fluvastatin and
lovastatin did not demonstrate an increased risk.
The researchers say several factors may explain the increased risk of
developing diabetes, including the possibility that certain statins
could block the release of insulin, the hormone that manages blood sugar
levels.
“Overall, the risk of developing diabetes among patients taking
statins appears to be low and may not outweigh the benefits of statin
therapy in moderate to high risk patients,” said Dr. Mamdani. “For
example, for every 1,000 persons treated with atorvastatin, only about
six to eight additional people will be diagnosed with diabetes relative
to those taking pravastatin. Both pravastatin and atorvastatin can be
used for most patients to prevent future cardiovascular events, however
our findings suggest pravastatin may confer a slightly lower risk of
incident diabetes. ”
| FDA mandates label change in 2012 |
In 2012, the US Food and Drug Administration mandated a labeling change to the entire drug class, issuing a warning that statins can raise blood sugar and HbA1c levels (pravastatin was exempted from the label change). The risk of diabetes began to gain traction first with the Justification for the Use of Statins in Primary Prevention: An Intervention Trial Evaluating Rosuvastatin (JUPITER) study, where investigators reported a 27% increase in the risk of
diabetes in patients taking rosuvastatin compared with placebo.
Other analyses and meta-analyses confirmed the increased risk with statins in JUPITER, with an analysis from the Women's Health Initiative (WHI) showing a 48% increased risk of diabetes among women, while an analysis of PROVE-IT, A to Z, TNT, IDEAL, and SEARCH showed that high-dose statin therapy increased the risk of diabetes by 12%. In addition, a similar meta-analysis found that statin therapy increased the risk of diabetes by 9%.
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