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Statins can cause a small increase in blood sugar levels, so people at high risk may develop diabetes sooner

An infographic

New evidence from the Cholesterol Treatment Trialists’ Collaboration has shown that statins can cause a small increase in blood sugar levels, which may mean that people who take statins and are already at high risk of diabetes may develop the condition sooner. The study is published in The Lancet Diabetes & Endocrinology.

Heart disease is a leading cause of premature death worldwide and having high levels of low-density lipoprotein (LDL) or ‘bad’ cholesterol is a major risk factor for developing heart disease. Previous clinical trials have shown that statins, a medicine that lowers levels of LDL cholesterol, can reduce the risk of heart attacks and strokes by approximately 25% for every 1mmol/L of LDL cholesterol reduction in people with and without diabetes.

Clinical trials have already demonstrated that taking statins can increase the risk of developing diabetes and that this risk is greater in people who need to take higher doses of statins to control their LDL cholesterol levels. This new study tried to find out more about how statins increase the risk of people developing diabetes, and how much the risk increases for different types of people. The study also tried to find out whether or not statins increase blood sugar levels in people who already have diabetes.

To answer these questions, the researchers analysed millions of data from thousands of participants in 23 large-scale randomised clinical trials of statin treatments. By looking at the data for every trial participant, the researchers were able to look at variations in the effects of statin therapy on diabetes status in different types of people, for example by age, sex, body mass index (BMI), and background risk of developing diabetes.

Key findings:

  • Statin therapy causes a small increase in glycaemia (blood sugar levels), which translates into a moderate increase in the rate at which individuals are diagnosed with new onset diabetes;
  • Participants who were given lower doses of statins had a 10% higher risk of developing newly diagnosed diabetes when compared with participants who were given a placebo. Participants who were given higher doses of statins had a 36% higher risk of diabetes compared with placebo;
  • For all statin doses, the increases in risk of new-onset diabetes appeared similar across all types of people, irrespective of age, sex, BMI, and blood sugar levels;
  • The same mechanism can also cause worsening blood sugar levels among those with diabetes: participants who already had diabetes at the start of the trials and who received lower doses of statins had a 10% greater risk of worsening blood sugar levels and those who received higher doses had a 24% greater risk of worsening blood sugar levels.

Christina Reith, Associate Professor at Oxford Population Health and Honorary Consultant in Pharmaceutical Medicine, said ‘This study demonstrates the likely mechanism by which statin therapy increases new cases of diabetes. We have confirmed that this is driven by a very small rise in blood sugar levels, leading some individuals receiving statins to cross over from just below to just above the threshold for diagnosing diabetes.’

David Preiss, Associate Professor at Oxford Population Health and Honorary Consultant in Metabolic Medicine, said ‘Our findings indicate that treatment with statins in routine clinical practice may lead to modest increases in the numbers of patients with diabetes. However, the diabetes-related risks arising from the small changes in worsening blood sugar levels resulting from statins are greatly outweighed by the known benefits of statins on major vascular events when the direct clinical consequences of these outcomes are taken into consideration.’

This study included data from 19 large randomised double-blind trials of statins versus a placebo, and four randomised double-blind trials of higher strength statins versus lower strength statins, involving 154,664 participants overall.