A huge new American study found that older women who use statin (cholesterol-lowering) drugs have a 48% greater chance of developing Type 2 diabetes. So should women take these drugs? What about women who already have diabetes? What about men?
This statin–diabetes connection has been found before. British researchers analyzed five trials and found a significant increase in risk of diabetes with higher doses of statins. A Scottish study published in The Lancet in 2010 showed that statin therapy at any dose was associated with a 9% increased risk of diabetes, much less than in the new study, but still significant.
What is the effect of statins on already-existing diabetes? It seems likely that they should make it worse, since they can help give diabetes to people who don’t have it. But we don’t actually know that yet. And the protective effect on blood vessels might outweigh whatever negative effect the drugs have on diabetes.
The current study looked at 153,840 women aged 50–79 years old. Those who were using statins at enrollment in the study had a 71% higher chance of developing diabetes during 14 years of follow-up. After adjusting for various factors, that excess risk dropped to 48%. The diabetes risk was seen for all types of statins, not any one particular drug.
The risk was especially strong for Asian women (78% increase in risk,) with Hispanic (57%) and white (49%) women also strongly affected. African-American women had only an 18% increased risk. Interestingly, women with the lowest body-mass index (BMI,) appeared to be at higher risk of diabetes if they were on statins, compared with obese women. Go figure.
Kirsten L. Johansen, MD, an editor of the Archives of Internal Medicine, said the increased risk of diabetes has “important implications for the balance of risk and benefit of statins.” Johansen wrote that, for people who do not have cardiovascular disease (CVD), previous studies have shown no benefit on all-cause mortality. Their cholesterol may go down, but they are just as likely to die. So maybe, for people who don’t yet have CVD, statins have more risks than benefits.
However, Lancet study author Naveed Sattar, PhD, and his fellow authors said the extra diabetes risk from statins is low, compared with the reduction in heart attacks and strokes. He thought statins should still be used to prevent CVD, not just treat it.
Benefits of Statins
Statins are the most widely prescribed drugs in the world. A single drug, atorvastatin (Lipitor) made Pfizer $12.4 billion in 2008. Statins inhibit an enzyme called HMG-CoA reductase, which helps create cholesterol in the liver. So statins lower cholesterol levels, which may reduce risk of blood vessel disease.
Statins do more than lower cholesterol. According to statin advocate Richard Fogoros, MD, the drugs have an anti-inflammatory effect, which is valuable for people with diabetes. They reduce blood clotting and may reduce formation of plaque on the walls of arteries. They help to stabilize existing plaques, so they don’t break off and cause heart attacks and strokes. They may even shrink those plaques.
Although previous studies have shown that people on statins don’t live longer than non-users do, newer data seems to show that they may. One study looked specifically at people with diabetes on statins. They found that a significant reduction in cholesterol led to a 9% reduction in death rate. People without diabetes had a 13% reduction. People who lowered cholesterol on statins had 21% fewer heart attacks and strokes (fatal or nonfatal,) whether they had diabetes or not.
Statins have side effects, of course, and some are serious. The most common are muscle aches and pains, which can become serious muscle damage. Effects on the liver, digestion, skin rashes, and others have also been reported.
Should You Take Them?
According to Dr. Fogoros, “Experts agree that [in people who have CVD], statins remain an extremely important part of reducing…risk. There is more controversy, however, in using high-dose statins in people who do not yet have CVD, but are at moderate risk of developing it.”
So the first thing to consider is, do you have CVD or not? CVD symptoms can include classic heart symptoms like chest pain (angina) and shortness of breath. They also include pain, numbness, weakness or coldness in your legs or arms. Sexual symptoms like erectile dysfunction and vaginal dryness can also be due to CVD. But many times CVD is not officially diagnosed until your condition worsens to the point of heart attack, stroke, or heart failure.
I think that realistically, anyone with Type 2 diabetes, and anyone who has had Type 1 for a long time probably has some CVD. But your cholesterol levels are also an important piece of the discussion. If your total cholesterol or your LDL (“bad”) cholesterol is not high, statins might not be worth the extra diabetes problems, even if you have some CVD.
Sex and ethnicity also matter. It seems from the recent studies that women gain less benefit from statins and have more risk of diabetes. Perhaps women should be slower to start statins than men. Also, the new study seems to show that Asian women are particularly likely to develop diabetes on statins, so perhaps they should be the last to take them. I couldn’t find studies looking at Asian men’s risk for diabetes on statins.
Although current recommendations are for most people with diabetes to be on statins, perhaps more research is needed, especially for women and people without CVD symptoms.