The goal of this clinical trial is to investigate whether metformin improves vascular function in individuals with prediabetes. The main questions it aims to answer are:
1. Does metformin improve large conduit artery endothelial function in individuals with prediabetes?
2. Does metformin improve microvascular endothelial function in individuals with prediabetes?
Researchers will compare metformin to a placebo to see if metformin improves vascular function in prediabetes.
The trial duration is 12 weeks. Participants will take metformin or a placebo once a day for 2 weeks. After 2 weeks, participants will take metformin or a placebo twice a day for the remaining 10 weeks. There will be a screening visit, two baseline visits, a 4-week safety visit, and two 12-week end-of-study visits. Adherence will be calculated from pill count and adverse events will be quantified via a questionnaire.