May 27, 2008
Diagnosis and Symptoms
Question from Salisbury, North Carolina, USA:
My 17 and a half year old son presented with a blood sugar of 426 mg/dl [23.7 mmol/L], urine ketones and typical symptoms of type 1 diabetes, polyuria, polyphagia, and polydipsia on February 22. He lost 10 pounds within about a month, but was beginning to train again for running. He did not go into DKA and presented with a virus at time of diagnosis. He started on multiple daily injections and counted carbohydrates/insulin ratios right from the beginning. He is athletic, running five to seven miles per day for his high school track team and lifts weights a few times a week. He has not taken NovoLog since March 19. He takes 10 units of Levemir in the morning with blood sugars ranging from 80 mg/dl [4.4 mmol/L] to 100 mg/dl [5.6 mmol/L] pre- and post- meals. He occasionally gets low, 55 mg/dl [3.1 mmol/L] to 70 mg/dl [3.9 mmol/L], generally in the evening hours from 7 to 9 p.m. I have just learned his GAD was negative. What is the significance of this in his diagnosis of type 1? Are there other causes for his condition?
Answer:
Antibody tests are only positive about 60 to 80% of the time, so there is not much significance in a negative antibody test. If you want to be thorough, one needs to test for islet cell antibodies, GAD-65 antibodies and IA2 antibodies, but it is a lot of money without much clinical utility. With classical symptoms and hyperglycemia, plus a nice response sounding like an early honeymoon phase, you are doing the right thing and going for tight control immediately. This may help save the damaged pancreas and allow more insulin production for a longer period of time. His exercise is also an excellent adjunct to his insulin and meal planning.
SB
