February 4, 2003
Diagnosis and Symptoms
Question from Ottawa, Canada:
I’m a 16 year old, slender white female with no family history of diabetes who was as diagnosed with type 1 diabetes while I was in a trip about five months ago. At that time, my fasting glucose was 240 mg/dl [13.3 mmol/L], I had a random glucose of 359 mg/dl [19.9 mmol/L] with large urine ketones, and I had lost 12 pounds in less than one week. I had no infection at time as well. The endocrinologist told me my symptoms were classic for type 1 and mentioned that my C-peptide was low. After a week, the doctor told me I was going through a heavy honeymoon period.
When I came back from the trip, I kept taking my NPH but I was going hypo a lot and my hemoglobin A1c was 4.6% so I stopped taking it. Now, my new endocrinologist says he does not think I have diabetes because my C-peptide is normal, my A1c is 4.6%, and I tested negative for islet cell antibodies. I had some blood work to confirm secondary hypothyroidism because my last TSH, T3, and T4 were low, but have not received the results yet.
I am very athletic and active, and I and have gained back the 12 pounds I lost when first diagnosed. My family doctor cannot understand my diagnosis since four months before it, my fasting glucose was 92 mg/dl [5.1 mmol/L] and a post meal was 104 mg/dl [5.8 mmol/L]. (I was pretty sick, and he could not figure out what was wrong).
My glucose does go up at least once a week (more than 200 mg/dl [11.1 mmol/L]) but it has been more down (less than 50 mg/dl [2.8 mmol/L]), and I usually wake up with a low. It is so erratic and unfortunately it does not matter how hard I try, I still get abnormal levels. Also my post-meal blood sugar is usually lower (about 150 mg/dl [8.3 mmol/L]) than my pre-meal (180 mg/dl [10 mmol/L]) even though I avoid fat.I cannot find any pattern, and neither can my doctor. I was wondering if I should ask my doctor for the other antibody tests. He mentioned that islet antibodies were the most common in type 1A diabetes and did not want to do the others. How long do I have these antibodies (insulin, GAD) present in my body after being diagnosed? What are other possible tests that would tell more about this situation?
Answer:
With an acute insulin dependent onset, it is almost certain that you have some form of type 1 diabetes. By far the most common is type 1A (autoimmune) which is characterised by a positive antibody test.
So the first step is to ask your doctor exactly what tests you had. You may have just had the immunofluorescent islet cell antibody screening test, but nowadays it is usual to use three tests: anti-GAD, anti-insulin, ICA 512 and sometimes anti-phogrin as well to reliably detect autoimmunity. If all of these are indeed negative then it is probable that you have type 1B or idiopathic diabetes. This is uncommon (less than5%) in new onset cases in Caucasian families, but occurs in slightly more than 50% of African American and Hispanic families.
It is important to make a distinction because in type IA, even though you may have quite an extended honeymoon period, ultimately you are going to need some form of insulin supplement for the rest of your life, whereas with type 1B, there is about a 50% chance that you can become insulin independent within a few weeks or months of the onset and that blood glucose control can then be sustained with simple oral medication such as metformin or even by just exercise and diet. Such evidence as there is however is that there is nonetheless a significant degree of insulin deficiency and that supplementation will again be needed at some stage.
From what you say, I think it improbable that you have still another form of diabetes and that any testing beyond the antibody testing will be needed.
DOB
