January 4, 2003
Diagnosis and Symptoms
Question from Tulsa, Oklahoma, USA:
Our 16 1/2 year old Caucasian daughter is 5 feet 5 inches tall, weighs 115 pounds, and was diagnosed with type�1 diabetes almost four years ago when she had all the typical symptoms and a blood sugar of 404 mg/dl [24.4 mmol/L]. She was put on minimal doses of Humalog with NPH (less than 5 units) twice a day but was experiencing lots of mid morning lows. We did this for two and a half years gradually decreasing the dose, and she would occasionally have a blood sugar of 170 or so mg/dl [9.4 mmol/L], but this was rare. She runs three to five miles/day, eats a healthy diet, and has low body fat.
She switched to Lantus (insulin glargine) a year ago, and things were much better with mostly normal or sometimes low blood sugars along with normal hemoglobin A1cs. Her doctor was doubting that she had diabetes and ran the three antibody tests all of which were negative. They did a glucose tolerance test which she failed. The highest blood sugar was 293 mg/dl [16.3 mmol/L], 30 minutes after the test, her sugar was 55 mg/dl [3.1 mmol/L], and her C-peptide was within normal limits. It seems she produces enough insulin, just delayed. Could my daughter have type 1B diabetes?
Answer:
Yes, this could be type�1B diabetes. A C-peptide value that is “within normal limits” does not really help me much but would tend to exclude type�2 diabetes. Does a difference in “labeling her” with type�1A (autoimmune) vs type 1B make a difference? Probably not clinically. although reassuring that her potential to develop DKA [diabetic ketoacidosis] is probably less. I would think that the routine vigorous exercise is helping tremendously.
DS
