The number of people taking cholesterol-lowering medications continues to grow. The percentage of adults aged 40 and older taking drugs to address high cholesterol rose from 20 percent to 28 percent between 2003 and 2012, according to the Centers for Disease Control and Prevention (CDC).

The use of statins increased from 18 percent to 26 percent, making them the most commonly used cholesterol-lowering drugs. By 2011-12, 93 percent of adults using a cholesterol-lowering medication used a statin. This increase may be related to the fact that statins have been shown to lower the risk of heart attack, stroke and premature death in men and women at risk for those events.

Women tend to develop heart disease about 10 years later (mid-70s) in life on average than men, and post-menopausal women with high cholesterol are usually prescribed statins. However, serious side effects associated with statins include myositis, elevated levels of creatine kinase, rhabdomyolysis and diabetes.

In a large meta-analysis in 2010, scientists found that statins increased the risk of diabetes by 9 percent. Now, a University of Queensland study has revealed that older women who take cholesterol-lowering statins increased their risk of developing diabetes, with the risk increasing 50 percent for women taking higher statin doses.

The objectives of the study were to evaluate and estimate the risk of new-onset diabetes associated with statin exposure in a cohort of elderly Australian women. Participants included 8,372 Australian women born between 1921 and 1926, alive at January 1, 2003, free of diabetes and eligible for data linkage. Statin exposure was ascertained based on prescriptions dispensed between July 2002 and August 2013.

Over 10 years of followup, 49 percent of the cohort had filled a prescription for statins, and 5 percent had initiated treatment for new-onset diabetes. Multivariable Cox regression showed statin exposure was associated with a higher risk of treatment for new-onset diabetes (hazard ratio 1.33; 95 percent confidence interval [CI] 1.04-1.70).

This equates to a number needed to harm (NNH) of 131 (95 percent CI 62-1,079) for five years of exposure to statins. Risk increased with increasing dose of statin from the hazard ratio of 1.17 (95 percent CI 0.84-1.65) for the lowest dose to 1.51 (95 percent CI 1.14-1.99) for the highest dose.

Cholesterol-lowering statins are prescribed to reduce the incidence of cardiovascular events, such as heart attacks and strokes. The majority of research on statins has been on 40- to 70-year-old men. Because research to date has rarely included elderly women, little is known about the risk of diabetes after statin exposure in this population.

In this study, 50 percent of women in their late 70s and 80s took statins, and 5 percent were diagnosed with new on-set diabetes. Most of the women progressed to higher doses of statins, and there was a dose effect, with the risk of diabetes increasing as the statin dosage increased.

Healthcare professionals need to carefully and regularly monitor their older female patients for increased blood glucose to detect and manage diabetes.