Our 10 year old daughter has gained over 40 pounds in the past 11 months, and her doctor said she has darker colored skin markings under her arms, which is a sign of adult diabetes. My daughter’s urine was negative for sugar, but the doctor did a (non-fasting) blood test without fasting. How accurate can a non-fasting blood sugar be? What does the skin discoloration mean?

A weight gain of 40 pounds in one year in a ten year old girl is about four times the normal maximum. Together with the typical skin changes of Acanthosis Nigricans, this suggests that your daughter has one of a number of forms of insulin resistance. The most probable is type�2 diabetes, which is increasingly being recognised in children.

A random blood sugar, as with any other blood sugar done in a clinical laboratory should be accurate to within two and three per cent. However, although it is an entirely reasonable first screening test for glucose intolerance, it is less reliable than a fasting value as an indication of diabetes because the timing of the most recent glucose load is not known.

I think you need to discuss the next step with the doctor; but it will involve some kind of a glucose tolerance test that includes serum insulin levels to confirm insulin resistance. Even if diabetes is confirmed treatment will not necessarily involve insulin, but it will mean starting an exercise schedule and instituting dietary control for which you will need the help of a dietitian who is familiar with this problem.

DOB