Prescribing metformin to type 2 diabetes patients prior to major surgery is associated with lower risk of mortality and readmission, a cohort study suggests.

US researchers obtained electronic health record data for adults with diabetes who underwent a major operation between 2010 and 2015 at 15 hospitals in one healthcare system in Pennsylvania.

The primary analysis included 5460 propensity-matched patients (mean age 68, 53% women), including 2730 with one or more prescriptions for metformin within 180 days before surgery and the same number who did not have metformin, followed for a median of over 4.5 years..

Preoperative metformin prescriptions were associated with a 28% adjusted reduced hazard for 90-day mortality and with reduced readmission at 30 and 90 days, according to the report in JAMA Surgery.