Question: A month ago I started taking 500 mg a day of Metformin for diabetes. My fasting blood sugar has actually risen. Is this unusual and what should I do?

Dr. Hibberd's answer:
Metformin is used to treat high blood sugar levels that are caused by Type 2 diabetes. This condition is characterized by insulin resistance, not insulin deficiency. Metformin does not help patients who have insulin-dependent or Type 1 diabetes because they cannot produce insulin from their pancreas gland. Type 1 diabetes is best controlled by insulin injections.
I presume you have Type 2 diabetes for our purposes here today, but you should make sure you have not been misdiagnosed.
Are you also controlling your diet as you were advised or have you grown diet-permissive now that you are on medication? Carefully follow the special meal plan your doctor gave you. This is a very important part of controlling your condition, and is necessary if the medicine is to work properly.
The dose of metformin you are using is very low, and most patients will need a gradual increase to 1,500 to 2,000 mg split into two doses daily. An improvement in your blood glucose control should have occurred in 1 to 2 weeks once this higher dosing is reached, but the full effect of blood glucose control may take up to 2 to 3 months to be reflected by your Hemoglobin A1C level.
You are probably not following a diet plan, and you likely need adjusted dosing of metformin to control your blood sugar levels. It is very important that your doctor check your progress at regular visits, especially during the first few weeks that you take this medicine. Expect periodic dose adjustment until goal glucoses are met. Chart a before meal and night-time glucose diary to review with your doctor.