Effect of metformin on outcome after acute ischemic stroke in patients with type 2 diabetes mellitus.

Introduction: Diabetes mellitus is a well-known risk factor for ischemic stroke and is associated with unfavorable outcome after stroke. Metformin is recommended as first-line treatment in these patients. Pre-stroke metformin use might have neuroprotective properties resulting in reduced stroke severity. However, results of the effects of pre-stroke metformin use on functional outcome are conflicting and has not been previously described in patients with type 2 diabetes mellitus regardless of stroke severity or revascularization treatment. In this study, we aimed to assess the association between metformin use and functional outcome in patients with type 2 diabetes mellitus and acute ischemic stroke.

Methods: We used data from patients with known type 2 diabetes mellitus who were admitted with acute ischemic stroke between 2017 and 2021 in the Isala Hospital Zwolle and Medisch Spectrum Twente (MST) Enschede, the Netherlands. The association between pre-stroke metformin use and favorable functional outcome at 3 months (defined as modified Rankin Scale (mRS) < 3) was expressed as Odds Ratios (ORs) with corresponding confidence intervals (CIs). Adjustments were made for age, sex, hyperglycemia on admission and revascularization treatment by means of multiple logistic regression.

Results: Nine hundred thirty seven patients were included of whom 592 patients (63%) used metformin. Six hundred seventy eight (74%) patients were hyperglycemic on admission. Median mRS was 3 (IQR 2-6) and 593 patients (63%) had a favorable outcome. Pre-stroke metformin use was associated with favorable outcome (aOR of 1.94 (95%- CI 1.45-2.59)).

Conclusion: In this study, we showed that pre-stroke metformin use was associated with favorable outcome after acute ischemic stroke in patients with diabetes mellitus type 2.