January 8, 2001
Diagnosis and Symptoms
Question from Katy, Texas, USA:
My son was diagnosed with type 1 diabetes six weeks ago. He entered the hospital with a blood sugar of 630 mg/dl [35 mmol/l] and 1+ ketones. His glycohemoglobin was 11.2% (it was 8.2% one month later), his insulin antibody was less than 2.0, and his islet cell antibody was less than 1.0. He entered his honeymoon within days and now requires 1.5 units of NPH after breakfast and nothing after dinner. He is running low at dinnertime, and sometimes at bedtime and 2 am. His blood sugars in the morning range from 90-110 mg/dl [5-6.1 mmol/l] and his lunch blood sugars range from 150-190 mg/dl [8.3-10.6 mmol/l]. Today, when we gave him his morning NPH, half of the insulin slipped out and he still ran low at dinner. Is it possible that my son might have type 1B diabetes? I have read that you do not suggest going off insulin all together. A C-peptide test was not run on him. Would this indicate whether he was type 1B? If he is type 1B, what is the treatment? Are there any illnesses whatsoever, that have been found to indicate the onset of diabetes without real diabetes?
The onset of diabetes in your son’s case was typically insulin dependent, and, as such, could be either type�1A (autoimmune) or type�1B (idiopathic) diabetes. The importance of defining the second group, apart perhaps from genetic counselling, is that about half become insulin independent at least for a time. Studies have shown that their ability to produce insulin is still compromised. The way to distinguish these two types at this stage is by the antibody test I am not familiar with the units that you report, although I assume that they imply a negative result both for anti-insulin and islet cell antibodies.
You should talk to your son’s diabetes doctor on this point or even contact the laboratory for their interpretation. Because of the difficulty in distinguishing the honeymoon period from type 1B becoming insulin independent at this stage, you might even want to get the more definitive test done which includes ICA-512, anti-insulin and anti-GAD antibodies.
In the meantime, you should know that only about 5% of Caucasian children with diabetes have type 1B, although it is a little over 50% in Hispanic and African American new onset cases. The underlying cause of the idiopathic form is not yet clearly understood. Some seem to have a variant autoimmune problem, and some are linked to chromosomal changes, but the majority are still not specifically defined.
As long as there is insulin dependence, the treatment of the two types is identical and involves trying to keep blood sugars as near to normal as possible without serious hypoglycemia. For those with a clearly negative antibody test profile, it is possible to gradually reduce the insulin dose and maintain control with diet and exercise, perhaps supplemented with oral agents.