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It came to attention a number of years ago that statins, a group of medications widely used to lower cholesterol and reduce heart attack and stroke risk, may increase the risk of developing diabetes (as blogged previously). However, we have been lacking some clarity on who is at higher risk of developing diabetes, whether low dose statin increases risk, exactly how much do sugars rise with statin, and what happens to blood sugar control in people who already have diabetes before statin therapy?

A large meta-analysis was recently published in The Lancet Diabetes & Endocrinology by the Cholesterol Treatment Trialists’ Collaboration to answer these questions. Authors included 19 randomized controlled trials of statin therapy, which encompassed over 123,000 participants, 21% with preexisting diabetes. Median follow up was 4.3 years. Trials of atorvastatin (Lipitor), rosuvastatin (Crestor), pravastatin (Pravachol), simvastatin (Zocor), lovastatin (Mevachor), and fluvastatin (Lescol) were included.

Compared with placebo, people allocated to low or medium dose statin therapy had a relative risk increase of 10% of developing diabetes. This sounds high, but it’s important to note that the absolute risk was very small: 1.3% of people per year in the statin group developed diabetes, vs 1.2% of people per year in the placebo group (thus, there was 1 additional diabetes case per 1,000 people treated per year with statin).

For high dose statin, the relative risk increase of developing new onset diabetes was 36% vs placebo. The absolute risk here was 4.8% per year with statin vs 3.5% with placebo, for an absolute increase in risk of 1.3% per year. Said another way, there were an additional 13 cases of diabetes per 1000 people treated with statin per year). (note: the placebo rate was higher in the high dose statin studies because there was more checking for diabetes conducted in these trials)

Using data from trials that included various statin doses in the same trial, more intensive statin therapy resulted in a 10% increase in new-onset diabetes – but again here, the absolute risk was low, with 2 additional cases of diabetes per 1,000 people per year.

Just how much did blood sugars rise? In people without diabetes at baseline, mean blood sugar increased by 0.04 mmol/L with any dose of statin. Hemoglobin A1c (diabetes report card) increased by 0.06% with low or medium dose statin, and 0.08% with high dose statin. These changes are extremely small. As one might expect, those at highest risk of developing diabetes were those who had sugars closest to the diabetes range to begin with.

For people with preexisting diabetes, the mean increase in blood sugar was 0.12 mmol/L for low or medium dose statin, and 0.22 mmol/L for high dose statin. A1c increased by 0.09% for low or medium dose statin, and 0.24% for high dose statin. Again, these changes are quite small, and quite easily manageable from the diabetes perspective.

So what does this mean for clinical practice? Despite the small increased risk of developing diabetes with statin therapy, the recommendations for using statins remain unchanged, due to their powerful capacity to reduce the risk of heart attacks, strokes, and cardiovascular death.

That being said, I think it’s important to recognize that there are some sensitivies around developing diabetes, which could understandably make some people reluctant to take statin therapy. Unfortunately, there can be a stigma around having a diagnosis of diabetes in the public eye and even amongst the health care profession, which we need to continue to work to break down. Having a diagnosis of diabetes can have health insurance implications as well. It’s important that health care providers understand these sensitivities and discuss any potential concerns with patients.

BOTTOM LINE: There is a small increase in risk of developing diabetes with statin therapy, which is important for people and their health care providers to know about. The benefits of statin therapy to reduce heart attack and stroke risk still clearly and heavily outweigh risks of treatment, so recommendations for statin therapy remain unchanged. Routine screening for diabetes remains important.

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