Your doctor is recommending that you start a statin medication to lower your cholesterol. She says: “Crestor will lower your bad cholesterol, and reduce the risk of plaque forming in your arteries which can cause coronary artery disease, heart attacks, and strokes.”
You’ve read all kinds of stuff online about statins, and one of the most recent was that statins cause diabetes. You reply: “No thanks, I’ve read that statins are bad for you and they can cause diabetes.”
Your doctor says: “That’s rare, but sure, blood sugars can go up with statins. A little. But you have prediabetes already, which does increase your risk of heart disease somewhat. While we certainly don’t want to tip you over into diabetes, your 10 year-risk of having a major cardiovascular event like a heart attack calculates to be about 13%. This is above the threshold that expert guidelines recommend for starting a statin. We would expect your 13% risk of bad events to be cut by 30% over the next 3-5 years if you start this medicine. And the longer you’re on this statin, the better. Sure, mildly higher blood sugars can increase your cardiovascular risk, too, but that slight increase in risk is already baked into numerous studies that keep showing that overall 30% plus reduction in heart problems.”
You reply: “Well, I’ve also read that statins can cause muscle problems, mess with our mitochondria, probably cause weight gain, and that your calculators overestimate risk such that nearly half of U.S. adults and up to 87% of men aged 60–75 would be eligible for statin treatment based on those calculators… which seems excessive, don’t you think, doctor?”
Your doctor replies: “Wow. Tadow. That was impressive. I admit that the totality of evidence regarding statins’ risks and benefits is overwhelming for one human brain to synthesize. So by necessity we are reductionist about it. Statins work best for higher risk people with longer time horizons, the calculators are the standard of care, and most cardiologists I know are taking a statin. They are pretty smart, right? Let’s both go home tonight and read this horribly complicated but great review article about statins. But for today let me at least answer your question about statins and diabetes risk based on a new meta-analysis published this year.”
You say: “Sounds good… like some vital and overlooked ideas your family doc might share, if only we had more time.”
Pooled data suggests that patients who take high-dose statins have about 1% higher risk annually for newly diagnosed diabetes.
Should we therefore abandon statins? Of course not. But here are some nuances, examined:
1. Diabetes is a common chronic disease that increases the risk of various serious health complications, including cardiovascular events, and doubles the risk of all-cause death. So we should take even one extra case of diabetes per 100 people treated with statins seriously.
2. The risk of cardiovascular consequences progressively increases as blood glucose levels rise, even below the diagnostic threshold for diabetes. So any increase in blood sugars needs to be taken seriously. But especially for people at high risk of cardiovascular disease, or those who already have it, trial after trial has found that statin benefits outweigh risks. Any increase in blood sugar is baked into the final results, which pretty consistently show about 30-40% reductions in cardiovascular disease and events for higher risk people treated. Benefits outweigh risks, and the diabetes risks are built into the final numbers.
3. Let’s get into the actual numbers. Put your boots on. This meta-analysis found that statin therapy:
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Increases the risk of developing new-onset diabetes by 10% for low/moderate-intensity statins.
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But this is a relative risk. Using our ninja statistical skills, we are reassured by the absolute risk increase here: only 1.3% of people on low intensity statins go on to develop diabetes per year treated, versus 1.2% on placebo. Therefore your added risk on these meds might be as low as a 0.1% added chance of developing diabetes.
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Low intensity statins include: simvastatin 10mg, fluvastatin 20 to 40 mg, lovastatin 20 mg, pitavastatin 1 mg, and pravastatin 10 to 20 mg.
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Moderate-intensity statins include atorvastatin 10 to 20 mg, rosuvastatin 5 to 10 mg, and simvastatin 20 to 40 mg, fluvastatin 80 mg, lovastatin 40 mg, pitavastatin 2 to 4 mg, and pravastatin 40 to 80 mg.
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Statin therapy increases the risk of developing new-onset diabetes by 36% for high-intensity statins.
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But this is a relative risk, too. The absolute risk here was only 4.8% of people on high intensity statins vs. 3.5% on placebo developing diabetes.
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People on high intensity statins usually have good reasons to do so, and we can see that their 3.5% baseline risk of developing diabetes is already higher. The data bore this out. New-onset diabetes was diagnosed more often in patients with prediabetes range blood sugars at baseline.
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High intensity statins include: atorvastatin 40 to 80 mg, and rosuvastatin 20 to 40 mg.
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Statins slightly worsen blood sugars overall.
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In the low/moderate intensity statin group, HbA1c levels were increased by only 0.06
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In the high intensity statin group HbA1c levels were increased by 0.08 points
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By way of example, if you are taking 5-10 mg of rosuvastatin you might expect your baseline HbA1c to go from 5.60 to 5.66. Is this really clinically significant? Depends on your global cardiovascular risk.
4. Despite this increased diabetes risk, the cardiovascular benefits of statins in high-risk individuals clearly outweigh the modest glucose level harm.
5. The findings emphasize the importance of holistic care, promoting strategies to prevent or delay diabetes (such as weight loss and exercise) when prescribing statins, and vigilance for adverse effects even with beneficial therapies.
6. As always, the dose makes a difference. It’s a good reminder to individualize the intensity and dosages of statins. Hopefully your primary care doc and/or cardiologist is juggling all these balls and keeping them in the air.
So, what did the researchers conclude with this meta-analysis? Should we be abandoning statins? Should we never start them? I think their conclusion is correct:
Any theoretical adverse effects of statins on cardiovascular risk that might arise from these small increases in glycemia (or, indeed, from any other mechanism) are already accounted for in the overall reduction in cardiovascular risk that is seen with statin therapy in these trials. Our analyses strongly suggest that the absolute benefits of statin therapy greatly outweigh any excess risks of diabetes associated with the small increase in glycaemia they induce.
Furthermore, as another expert physician reviewer stated in New England Journal Watch:
(Much more benefit than risk with statins) is certainly true for secondary prevention (in people who already have cardiovascular disease) and for primary prevention in people at high risk. But it might not be true for primary prevention in patients with borderline indications for statin therapy.
Ironically this whole issue came up in my practice this week. A man in his 70’s who is not obese, exercises regularly, and has never had a heart attack is maintained on a high intensity statin. He had a cardiac catheterization that showed 30-50% narrowing of his coronary arteries. Since starting a high intensity statin with his cardiologist a couple years ago, he has drifted upwards into the diabetic range. Coincidence? His cardiologist acknowledged the possibility that his statin could be contributing, but balked at making any changes. I am reaching out to his cardiologist today to discuss reducing the intensity of his statin in light of the above meta-analysis, and as part of a holistic strategy including refocusing on diet, exercise, and weight loss. I’ll keep you posted in the comments on the Examined website about how that important discussion goes.
And so in summary, keep blood sugar on the radar with statin medications. Take only the dose and intensity that makes sense for your situation and risk factors in consultation with your doc. And never rely on medications over lifestyle improvements like exercise, weight loss, and a heart healthy diet. There is no way a doctor can discuss all this nuance in a typical office visit, but we try to hit the major themes and stay in our lanes. I hope this helps you in your discussions, too!
Most cardiologists love when their patients cite meta-analyses from The Lancet, right?
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This post was first published on my site Examined. I’m trying out a 1 month, complimentary, upgraded membership —> free for Daily Kos homies. It’s been so awesome cross-posting some relevant stuff here. But this trial will give you full access to everything I’ve written/podcasted over the past 3 years about vital and overlooked ideas in primary care. If you like it, please stay! Link.