My 11 year old friend has begun metformin (500 mg twice a day) to possibly prevent diabetes and is not scheduled to see the doctor again for six months which seems like a long time to wait. Once metformin begins, should blood sugar be tested and how often? What studies have been done? There is very little information on this, and nothing I could find for pediatric use.

I imagine that your 11 year old friend who is overweight perhaps has a family history of type 2 diabetes, a condition becoming increasingly common in the young. I also assume that, because of this, his fasting blood sugar was tested and found to be above the normal limit of 110 mg/dl [6.1 mmol/L] but lower than 126 mg/dl [7.0 mmol/L] which would be diagnostic of diabetes. Assuming that this result was repeated it would be reasonable to start metformin to help keep the blood sugars within the normal range.

However, to prevent clinical diabetes, it would be necessary also to have an active plan for weight reduction and exercise. You should perhaps discuss with your friend’s parents exactly what his doctor said because in the matter of blood sugar estimations that is really for him/her to decide. In general terms though, I would have thought that it would be a good idea to get a home blood glucose monitor and to do a fasting test once a week. Then if the glucose levels reached the ‘diabetic’ range or if they became consistently normal, I would think it appropriate to review the need for metformin earlier than the proposed six month interval.

On the issue of preventing type 1A (autoimmune) diabetes, a great deal of research has been done, but the results have so far been disappointing. Quite recently, two very large studies turned out to be of no value. Nonetheless, there has been progress in defining who is genetically susceptible and finding out what the additional environmental triggers are (early exposure to cow’s milk, lack of vitamin D, etc.). In the next five years, I think we shall learn to be much more successful as interventions are able to start earlier and some good studies along these lines have already started.

DOB