Study Finds Majority of Patients Using Insulin Glargine Past Recommended Expiration

Insulin glargine should not be used past 28 days after the vial is first used, but 80% of patients do. 

More than 80% of Medicaid patients in a new study took insulin glargine past its recommended 28-day expiration date after the vial is first used.

"That is a huge number, which clearly shows the lack of education about this from the physician’s office or pharmacy," Elizabeth Unni, PhD, MBA, BPharm, an associate professor of pharmaceutical sciences at the College of Pharmacy at Roseman University of Health Sciences told Drug Topics.

The study was published in the Journal of the American Pharmacists Association.  Unni, a coauthor, and her colleagues at Molina Healthcare, identified 269 Medicaid patients with diabetes who were taking insulin glargine in Utah, Ohio, Michigan and California to learn more about patient use habits.

"One potential reason for patients to use insulin glargine beyond the 28-day limit can be the cost of the medicine," Unni said. "So, we targeted Medicaid population because these patients either have no copay or a very small copay. This way, we were able to control for cost as the reason for the extended use of insulin glargine."

Extended use of the medication is a concern, she said, because after 28-day from when the vial is first used, there is no guarantee of the effectiveness of insulin glargine. If effectiveness is altered, it could impact the ability of insulin glargine to sufficiently control the blood sugar level.


Researchers found that 81% of those included in the study used insulin glargine past its recommended use-by date, with the mean use of 43 days.

In the second phase of the study, they examined the reason why patients were using the medication past its recommended use-by date. Although they were only able to include feedback from 12 patients, Unni said the most common reason for extended use was a lack of awareness. Patients either weren't told to discard it at 28 days or didn't remember being told.

"Those who were discarding it at 28 days clearly remembered either a pharmacist or diabetes educator educating them about it," Unni said.

More research is needed to determine the clinical efficacy of the drug after 28 days, but Unni said this recent study highlights the need for increased communication efforts by physicians and pharmacists about the manufacturer recommendations.

"If the pharmacy database is showing that they are [using] the insulin glargine later than 28 days, it can be a good conversation starter," she said. "The pharmacists can use that opportunity to educate the patients about discarding the vial after 28 days, medication adherence, and any other barriers they may have in taking their diabetes medicines as prescribed."