A meta-analysis of observational studies published in the journal Nutrition, Metabolism & Cardiovascular Diseases has found that cholesterol-lowering statin drugs raise the risk of developing type 2 diabetes by 44%.
Statins remain the most-prescribed drugs in Australia: atorvastatin (Lipitor) and rosuvastatin (Crestor) led the top 10 drugs by prescription count in 2015, with 10 557 512 and 9 432 332 prescriptions respectively.
Different types of statin drugs carry different risks of developing diabetes. Users of rosuvastatin had a 61% higher risk of developing diabetes than non-statin users, while for atorvastatin users the risk was 49% higher. Simvastatin (Zocor) was the least diabetogenic (diabetes-inducing), conferring a 38% higher risk.
Randomised clinical trials (RCTs) of statin drugs (in which half the participants are given a statin drug and the other half are given a placebo or a different drug) have come up with much lower estimates of the increased risk of diabetes associated with these drugs – somewhere in the order of 12%.
But the authors of this meta-analysis point out that RCTs are actually not set up to measure diabetes risk, and so tend to underestimate it.
Observational studies, on the other hand, have far higher numbers of participants, the participants are much more typical of the types of patients who will be prescribed the drug once it’s released onto the market (unlike participants in RCTs, which carefully weed out subjects who are at highest risk of adverse events), and much longer follow-up periods, making them better suited to detecting adverse events such as development of diabetes.
In all, 20 observational studies were included in the meta-analysis, with a follow-up duration ranging from 2 to 20 years.
Defenders of statins have suggested that high cholesterol puts people at increased risk of both cardiovascular disease and diabetes, and that the sickest patients are most likely to be prescribed statins, and may be at higher risk of developing diabetes whether they take the drug or not.
But the authors pointed out that many of the studies they analysed controlled for these potential confounding factors, for example by only enrolling participants who had high cholesterol levels and comparing diabetes risk in those who took statins to those who didn’t. Also, there was a continuous relationship between statin compliance and diabetes risk – in other words, the better participants were at taking their drug regularly, the higher their risk of developing diabetes.
It’s not entirely clear why statins raise the risk of developing diabetes, but there are several lines of inquiry. Firstly, in RCTs of statins, their use is associated with weight gain, which is a risk factor for developing diabetes. Secondly, lowering LDL cholesterol in itself may raise the risk of diabetes. Thirdly, laboratory studies have shown that stain drugs damage the β cells in the pancreas that produce insulin. Fourthly, statins interfere with the activity of insulin in multiple ways, leading to insulin resistance. And fifthly, by interfering with cholesterol production, statins also inhibit the synthesis of several other biological compounds that are involved in glucose metabolism.
The great irony in this whole sorry tale, of course, is that statin drugs are prescribed to lower cholesterol and therefore reduce the risk of cardiovascular disease, such as heart attacks and strokes. But having diabetes more than doubles the risk of having a heart attack overall, and more than quadruples it in women. For Asians and South Asians who become diabetic, the increased risk of having a heart attack is even more dramatic than for people of European descent.
If you needed a perfect illustration of the sheer folly of the current medical approach of ‘risk factor management’, this is it. Instead of educating patients about the causes of their elevated cholesterol level – their poor dietary habits and sedentary lifestyle – and coaching them to make healthier choices, doctors write a prescription for a drug that raises the risk of developing a serious chronic disease that in turn raises the risk of developing cardiovascular disease… not to mention blindness, kidney failure, sexual dysfunction, limb amputation and a host of other nasty complication, as the authors of the meta-analysis point out:
“We should consider that the diabetic patient is not only characterized by an increased cardiovascular risk, but also by other complications, the need for drugs, and worse quality of life. These aspects are difficult to quantify, but might result in a clinical and economic impact.”
In stark contrast, when people with high cholesterol adopt an oil-free wholefood plant-based diet, and increase their activity level, their risk of diabetes actually decreases, along with their risk of cardiovascular disease, high blood pressure, obesity and several types of cancer.
It takes enormous technical cleverness to identify the enzyme – HMG-CoA reductase – which is required for our bodies to make their own cholesterol, and then develop a drug that targets that enzyme in order to shut off cholesterol production and lower serum cholesterol level. Unfortunately, cleverness is not wisdom. It isn’t wise to write people a permission slip to continue indulging in their bad habits, which is effectively what writing a prescription for a statin drug equates to.
Instead, the entire practice of medicine needs to be overhauled so that people are told the truth about the connection between their daily habits of living and their health outcomes, and provided with assistance to change those habits. That’s Lifestyle Medicine – using lifestyle change not just to prevent, but also to treat and even reverse chronic disease.
The bottom line is that health comes from healthful living, not out of a bottle of pills.
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