New Study Finds Diabetes Risk Rises With Statin Adherence

Miriam E. Tucker

July 17, 2014

The risk of new-onset type 2 diabetes rises with adherence to statin therapy, providing further confirmation of the previously reported link. However, the benefits of statins still "clearly" outweigh the risks, according to a large new population-based study and analysis.

The findings were published online June 26 in Diabetes Care by Giovanni Corrao, PhD, of the division of biostatistics, epidemiology, and public health, University of Milano-Bicocca, Milan, Italy, and colleagues.

The study, involving a healthcare utilization database of 115,709 statin-using patients with an average 6.4 years of follow-up per patient, "extends earlier findings of an increased risk of diabetes with statin therapy by providing evidence of a clear-cut association between adherence to statin therapy and risk of new-onset diabetes in a real-world setting," Dr Corrao and colleagues write.

But, they also note, it appears from event-based investigations "that benefits of statins in reducing [cardiovascular] events clearly overwhelm the diabetes risk."

Naveed Sattar, MD, PhD, professor of metabolic medicine at the University of Glasgow, Scotland, told Medscape Medical News that this study further supports the conclusion of a recent clinical trial review from the diabetes subpanel of the US National Lipid Association Expert Panel on Statin Safety, for which he was senior author.

Commenting on the new study, Dr. Sattar said: "It's observational, and with this, one always has the issue of potential confounding, which is hard to ever fully overcome with such designs. That noted, this...does seem to suggest an...association using compliance...so it fits with the trial data."

He also agreed with the author's benefit/risk conclusion. "The vascular benefits of statins remain important, and one must remember that good compliance will also lead to lower cardiovascular disease [CVD] risk....Some will suggest that the diabetes risk in some will match the CVD benefits, especially on a high-dose statin, but one must remember that preventing 1 hard CVD event is not 'outweighed or equaled' by 1 extra diabetes case, so the arguments have to be carefully considered," he told Medscape Medical News.

No Difference Between Different Potency Statins

In the new study, the patients had a mean age of 62 years at the time of first statin prescription. None had been diagnosed with diabetes prior to that time. During follow-up, 9.6% of the entire cohort developed diabetes, at a rate of 14.9 per 1000 person-years.

Adherence was defined by the proportion of days during which the medication was available to the patient divided by the number of days of follow-up, called the "proportion of days covered (PDC)". Adherence was very low (PDC less than 25%) in 37.1% of patients, low (25% – 49%) in 20.2%, intermediate (50% – 75%) in 18.4%, and high (> 75%) in 24.4% of the participants.

After adjustment for age (continuous), sex, first-line statin therapy, concomitant use of other drugs, history of CVD, and Charlson morbidity index score category, the hazard ratios for developing diabetes compared with the very low adherence group were 1.12 for low adherence, 1.21 for intermediate, and 1.32 for high adherence. All were statistically significant (95% confidence intervals did not include 1).

Statins used by participants included simvastatin, pravastatin, fluvastatin, atorvastatin, and rosuvastatin (Crestor, AstraZeneca): a separate analysis of high- vs low-potency statins did not show a statistically significant difference in the statin effect on diabetes risk.

Benefit/Risk Calculation

Based on these data, the authors estimate that about 280 patients would have to be continuously treated to cause 1 case of diabetes per year.

In contrast, a meta-analysis of 7 randomized controlled trials found that statins decreased 1 major cardiovascular and cerebrovascular event for every 40 patients treated.

"Thus, the CV protection offered by statins appears to markedly outweigh the increased incidence of diabetes," Dr. Corrao and colleagues state.

Dr. Sattar told Medscape Medical News, "Essentially, the statin-diabetes effect is real. The key message for clinicians is to reiterate strongly that patients can offset diabetes risk once on a statin by taking lifestyle changes seriously."

Dr. Corrao has no relevant financial relationships. Disclosures for the coauthors are listed in the article. Sattar is on advisory boards for Kowa, Sanofi, and Amgen .

Diabetes Care. Published online June 26, 2014. Abstract

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