My ten year old son is having low blood sugars. His symptoms were numb/shaky legs. He does not have diabetes. His insulin and proinsulin levels were almost three times the high normal range at two and three during the five hour glucose tolerance test. After two months of glucose monitoring daily, his endocrinologist has prescribed diazoxide [a prescription medication that can raise blood sugar levels].

I am hesitant to start medication without further for a reason as to why his blood sugar is low. He has had readings as low as 24 mg/dl [1.3 mmol/L] and “lo” on the tester. Now, with eating consistently every two to three hours and very little refined sugar, he usually has two or three readings a week in the mid 50s mg/dl [2.8 mmol/L] to upper 60s [mg/dl [3.3 mmol/L]. Quite a few readings are in the 70s mg/dl [3.9 mmol/L]. He will have readings in the normal range probably more than half the time. Is my hesitation of treating with diazoxide before any further blood work justified? Am I overly worried about the medication? Will the medication possible alter any growth hormone or cortisone deficiency tests my doctor has mentioned?

On the face of it, there is good evidence that your son has hyperinsulinemic hypoglycemia. To avoid having to look for rare metabolic causes of his late onset hypoglycemia, I think it would be important to, first of all, make absolutely sure that the laboratory figures really are out of range. I say this only because insulin levels in children can be very variable. Also, if most of the blood sugars have been done on a home meter, I would again like to be sure of their accuracy. I am sure that this will have already been done though.The next question may be to see if the blood sugar levels can be brought a little more into the normal range. A simple step could be the addition of unhydrolysed starch into the diet at night, and, perhaps also, the use of the drug nifedipine which has long had a role as a calcium channel blocker in the management of hypertension.

If the hyperinsulinemia diagnosis is valid, then it seems to me to be important to give a first priority to ascertaining the reason for it. It is unlikely to be due to any abnormality in the pituitary/adrenal axis so that I think you need to discuss with your son’s endocrinologist whether it might be due to an insulinoma, which might be diagnosed radiologically using several modalities like MRI and CT scan and ultrasound. If the blood sugar control gets more difficult, exploratory surgery. may be indicated, a procedure that could also exclude the very rare adult type nesidioblastosis, a condition of hyperplasia of insulin producing cells normally only seen in infants.

DOB