August 23, 2003
Diagnosis and Symptoms
Question from Michigan, USA:
My daughter was in the hospital with a blood glucose of over 400 mg/dl [22.2 mmol/L] which the doctor said was a classic case of type 1 diabetes, but since then blood glucose has been within normal range, except for a few high postprandial readings. Her pediatrician tested her A1c, and not only was it within normal range, it was low (4.9%). He also did two antibody tests, and the islet cell antibodies was negative, but the GAD test was borderline. The range from the lab was equal to or greater than 1.0 was positive, and her result was equal to or less than 1.0. Her pediatrician interpreted that result as negative, but I think her result could be interpreted as positive. The pediatrician says that she does not have diabetes and that her high blood glucose levels were from eating carbohydrates and sugar or from stress. I am concerned that she may be developing diabetes.
Answer:
An anti-GAD test that is only just at the upper limit of normal is most certainly not diagnostic of type 1A (autoimmune) diabetes, which is the most common form in childhood in North America. However, the initial blood sugar of 400 mg/dl [22.2 mmol/L] does mean that your daughter has some form of diabetes. Perhaps the most likely diagnosis is type 1B diabetes, which only occurs in about 5% of new onset cases in Caucasian families but is seen in just over 50% in Hispanic or African American families. The distinction, which depends on a typical onset of type 1 diabetes but with negative antibody tests, is of some importance because many of these latter cases may become insulin independent or able to be controlled on aoral hypoglycemic agents, or even with diet and exercise, at least for a number of years. It is also possible that this is type 2 diabetes which a strong family history, being overweight and a normal or slightly high serum C-peptide level might suggest this. There are other rarer possibilities.
What is important is not the specific diagnosis but the ability to keep blood sugars as near to normal as possible, which you seem to have made a very good start with.
DOB
