Metformin typically starts lowering blood sugar within the first week of treatment, with some effects seen as early as 48 hours after the first dose. However, it may take about 2 to 3 months to experience the full glucose- lowering effect and to see significant changes in lab tests such as HbA1c, which reflects average blood sugar over the past 2 to 3 months
. Key points on timing:
- Peak plasma concentrations occur within 1–3 hours for immediate-release metformin and 4–8 hours for extended-release formulations
- Initial blood sugar improvements can be observed within the first week, sometimes within 48 hours
- Full efficacy, including sustained blood sugar control and HbA1c reduction, generally takes 2 to 3 months
- Metformin’s mechanisms involve reducing liver glucose production, decreasing intestinal glucose absorption, and increasing insulin sensitivity, which contribute to its gradual effect
Additional notes:
- The duration of action varies by formulation: immediate-release lasts about 6 hours, extended-release about 12 hours
- Signs that metformin is working include lower blood sugar, reduced HbA1c, modest weight loss, and improved cholesterol levels
- If blood sugar remains high after several weeks, a doctor may adjust the dose or add other medications
In summary, while metformin begins to work quickly in lowering blood sugar, patients usually need to take it consistently for several weeks to months to see its full benefits.
