Warfarin and Diabetic Drugs Mix Increases Hypoglycemia Risk

A new study warns that a combination of warfarin and sulfonylurea anti-diabetic drugs is linked to increased hospitalization for serious hypoglycemic events and insulin shock.

Researchers at the University of Southern California (USC; Los Angeles, USA) and Harvard Medical School (Boston, MA, USA) conducted a retrospective cohort analysis of pharmacy and medical claims to examine the association between use of warfarin with common sulfonylureas and serious hypoglycemic events. The study included 465,918 Medicare beneficiaries with diabetes (65 years of age and older) who filled a prescription for glipizide or glimepiride between 2006 and 2011; 71,895 (15.4%) of these patients also filled a prescription for warfarin.

The results showed that hospital admissions or emergency department visits for hypoglycemia were 22% higher in diabetic patients during concurrent warfarin use than without warfarin use. The risk was higher among those using warfarin for the first time, as well as in those aged 65-74 years. Concurrent use of warfarin and glipizide/glimepiride was also associated with hospital admission or emergency department (ED) visits for fall-related fractures and altered consciousness/mental status. The study was published on December 7, 2015, in BMJ.

“Pharmacists don't need to change patient instructions; what it does require is for pharmacists and other clinicians to be more vigilant when a sulfonylurea is added to a regiment that includes warfarin, as well as when a patient who is taking both has a change in their medical status,” said study co-author USC professor of clinical pharmacy and gerontology Bradley Williams, PharmD. “I think additional research into the potential interactions between medications for diabetes and warfarin, as well as other drugs that affect blood clotting, is warranted because of the potential consequences of excessive bleeding.”

Sulfonylureas are a class of organic compounds used in the management of diabetes mellitus type 2 that act by increasing insulin release from beta cells in the pancreas. Sulfonylureas, as opposed to metformin and other newer treatment agents, may induce hypoglycemia as a result of excesses in insulin production and release. This typically occurs if the dose is too high, and the patient is fasting. Warfarin can also intensify their effects and induce hypoglycemia.

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University of Southern California
Harvard Medical School