My 14 year old daughter was diagnosed with type 1 diabetes about a year ago, my 15 year old son was diagnosed with type 1about a year and one-half ago, and my husband (their father) has had type 1 for 20 years. My son never seemed to have a honeymoon period, is on an insulin pump, and is doing very well.

My question concerns my daughter. She self-identified symptoms of increased thirst and urination, and a weight loss of about 14 pounds at that time, after watching her older brother go through it six months earlier. For a month, we checked her fasting blood sugars and found them to be 90-130 mg/dl [5-7.2 mmol/L]. We discussed this with our pediatric endocrinologist who suggested we do a one-hour and two-hour postprandial test. We found blood sugars of 400 mg/dl [22.2 mmol/L] and 500 mg/dl [27.8 mmol/L] up to three hours postprandial. She was started on insulin and is currently she taking 3 units of 75/25 by pen in the morning, and 2 units in the evening. Her C-peptide was 700 and her antibody test was negative. She is taking niacinamide (but not very regularly) as recommended by her doctor. She continues to have many blood sugars over 150 mg/dl [8.3 mmol/L], and some up in the 400s mg/dl [22.2 mmol/L], but usually at times other than fasting. Fastings are usually 90-140 mg/dl [5-7.8 mmol/L]. She is 5 feet 7 inches tall and weighs 180 pounds. She is very athletic and active and has gained back the 14 pounds she lost when first diagnosed. Her doctor believes that we caught this very, very early due to our knowledge of the disease. Is she going through a long honeymoon period? Is it possible she actually has type 2? There is no history of this in the family at all. Her doctor believes that with the history of type 1 this is probably what she has. She consulted with some other specialists and they agreed, but no one is really sure. Can you give me your opinion?

I can understand the dilemma. On the face of it, your daughter really has to have type 1A (autoimmune) diabetes because of the family history. Giving niacinamide and very small doses of insulin is entirely appropriate at this stage, but here are some questions to discuss with her doctor:

The blood sugar pattern that you give is abnormal, and I wonder what the HbA1c test shows. If it is above 6.5%, it might be worth considering a small increase in the insulin dose to bring this down to normal. Later in the year, when it will be available in the US, a single daily dose of the new insulin Lantus (insulin glargine) would be something to consider. At the moment, her dose is less than 0.1 units per kilogram if body weight per day which is very small but of value immunologically even if it isn’t contributing all that much to normalising blood sugars.
I think you should ask for more details about the antibody test. Was it a single assay of islet cell antibodies by the older immunofluorescent technique or was it the usual series of tests done nowadays which is for three antibodies to GAD and to insulin and for ICA512? If it was the newer technique, but not for all three antibodies a negative test would not rule out type 1A diabetes. In addition, whilst you’re asking about lab work, it looks as though the decimal point in the C-peptide assay result has got lost, but I’m sure it is normal.
I wonder if your husband and your son had antibody tests. If one of them did, and it was positive, then that strengthens the probability that everyone has autoimmune diabetes. If there was no positive test, then it is possible that all three members of the family have what is called type 1B diabetes. These children present in the same way as the autoimmune form, but some of them can manage without insulin after a number of months, and none of them have positive antibody tests. The exact underlying pathology is not yet worked out; but in some of them it is linked to a chromosomal change which could account for the inheritance pattern.
Your daughter is both tall and heavy for her age, but when I worked out her body mass index (BMI), it was only 23 which is near the upper range of normal. That goes a long way to ruling out type 2 diabetes as does her enthusiasm for athletics and again the family history.

Having said all this, I think that your daughter is being well-managed, and I have to add that whilst having an exact diagnosis may be intellectually soothing, it makes very little difference to treatment which has to be aimed at keeping blood sugars as near to normal as possible.

DOB