Metformin typically begins to lower blood sugar levels within 48 hours of starting treatment. However, while some effects can be seen early, it usually takes about 2 to 3 months to achieve its full blood sugar control effect. The decrease in fasting blood glucose can start within the first week and continues to improve over several weeks. The medication works gradually, with its peak effects on blood sugar often noted after several weeks to months, depending on the individual's response and dosage. Additionally, noticeable signs such as improvements in HbA1c levels (a longer-term blood sugar marker) may take a few months to appear. Metformin's full benefits are usually seen when combined consistently with diet, exercise, and medical supervision. In summary:

• Metformin begins working within 48 hours to a few days.
• Significant blood sugar reductions can be noted within the first week.
• Full effects typically take 2 to 3 months to manifest.
• It works best with lifestyle changes and adherence to the prescribed regimen.