My seven year old daughter has had periodic episodes resembling ketotic hypoglycemia–lethargy, clamminess, shakiness in the morning and during illness when she has not eaten. These episodes first began when she was about nine months old and have recurred off and on throughout her life (perhaps 15 episodes total). From the very first episode, I suspected low blood sugar and always gave her juice and food immediately, and she quickly recovered. This week, during her annual physical, I raised this issue again with her pediatrician. I am particularly concerned because my daughter’s aunt (my husband’s sister) has had type 1 diabetes since the age of 12, and I have read some information that hypoglycemia can be linked with diabetes. In response to my query, her doctor recommended a three-hour glucose tolerance test (GTT).

The GTT will be fairly traumatic for my daughter. Do you think that this test will provide important information? If it will simply confirm a diagnosis of ketotic hypoglycemia, I’d rather spare my daughter the test. Do you think the GTT is worth doing at this point?

I think that if you asked a dozen pediatric endocrinologists, you might get 13 answers to your question…..

My response is this:

I find an oral glucose tolerance (OGTT) RARELY helpful in pediatric endocrinology. It is often done INCORRECTLY by family physicians, general pediatricians, and most laboratories. See similar questions on this web site about the pitfalls and specifics of OGTTs. The biggest errors typically are:

poor preparation of patients: there should be specific instructions encompassing consuming at least 60% of the calories as carbohydrates in the three days before the test;

inappropriate glucose dosing, usually excessive (the proper dose is specific as 1.75 gm per kilogram body weight NOT TO EXCEED a total dose of 75 grams. Often, 100 grams are given as when testing a pregnant woman for gestational diabetes);

failure to measure insulin concurrently with the glucose levels (insulin would be especially important to measure when doing an OGTT for HYPOglycemia)

measuring glucose levels during the test with a small glucometer rather than formally from venous serum samples in the laboratory.

That said, I do not think that an OGTT is actually required for confirming ketotic hypoglycemia. Confirmation of urine or serum ketones concomitantly with HYPOglycemia during symptoms should be adequate. The OGTT would be used to help look for “other” issues. But, even so, there are probably better procedures, including the potential problematic “prolonged (usually 24-36 hours) supervised fast.”

There certainly are anecdotal reports of hypoglycemia preceding the development of diabetes, but I do not recall ever seeing a convincing medical series or study on this. Personally, before I would put the child through the rigors of a properly done OGTT for this issue, I would ask for either a referral to a pediatric endocrinologist or least have your pediatrician confer with one as to an optimal evaluation.

I will add that we are learning more about some forms of so-called ketotic hypoglycemia and some seemingly are due to mild irregularities leading to inappropriate production of insulin. These typically can be screened for easily (for instance, by measuring the ammonia level in blood) and may be sometimes very easily treated with medication. At age seven, unless your daughter is particularly thin, she would be leaving the age of more typical ketotic hypoglycemia. She could have had that and now has “something else.” Furthermore, if her episodes are pretty infrequent, non-debilitating, and easily addressed now and you and she know how to try to prevent the spells (frequent small meals, minimizing routine intake of simple sugars and maximizing intake of more complex starches and proteins), then perhaps you might be willing to forego any more in-depth evaluation. I’d confer with your local pediatric endocrinologist for a more in-depth history and physical examination.

Let us know what you learn!

DS