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September 4, 2003

Diagnosis and Symptoms

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Question from Grand Rapids, Michigan, USA:

My son had no symptoms of diabetes, but eight weeks ago, our pediatrician found sugar in my son’s urine during a routine physical exam. The amount of sugar in the urine was characterized as above normal but not really high (2%).

My son has just turned 6 years old. He is not and has never been overweight. He is usually at the 85% on height and 80% on weight (he weighs 51 lbs). My side of the family has some Type 2 diabetes. My grandmother and several great aunts and an uncle had diabetes. They were all overweight. My mother was quite overweight late in her life, but she never mentioned having diabetes. She died 10 years ago at the age of 72 with blood clot problems. I have never been overweight and I don’t have diabetes (I have regular checkups). My husband knows of no diabetes in his family.

We followed up the next day with a fasting blood glucose which was 118 mg/dl [6.6 mmol/L]. and a few days later, on order of a pediatric endocrinologist, we repeated the fasting blood glucose and also had tests for C-peptide, A1c, and GAD 65 antibodies. On the basis of the C-Peptide (1.2 ng/ml), the A1c (7.9%), and the fasting blood glucose (130 mg/dl [7.2 mmol/L]), my son was diagnosed with type diabetes and put on 2 units of Lantus at bedtime. A few days later, the GAD test results came back and the endocrinologist said that the results were negative (0.01 nmols/l). He then went on to say that maybe our son can eventually go on oral medication and mentioned MODY.

I was completely disoriented by this information, and I have been trying to determine what my son’s prognosis might be. With the 2 units of Lantus, his pre-meal readings are all 80-100 mg/dl [4.4-5.6 mmol/L] with the bedtime readings creeping up to about 130 mg/dl [7.2 mmol/L] near the time the Lantus is waning. I have some type 2 diabetes in my family, but none in my generation. Can you help me ask the right questions of my son’s doctor? Can you give me more information or your opinion?

Answer:

From: DTeam Staff

I believe that the first diagnosis of type 1 diabetes was correct and was not only by far the most probable one. It was supported by the fasting blood sugar, the C-peptide, and the hemoglobin A1c level. I also think that your son’s problem was picked up fortuitously just at the point that the preclinical stage was moving to the insulin dependent one and that the use of Lantus is entirely appropriate.

However, I believe that it is important to look further at the apparently negative anti-GAD antibody test before moving to consider Maturity Onset Diabetes of the Young or type 2, and other rarer forms of childhood diabetes. First of all, laboratories are now supposed to report antibody results not as a single figure but as a variation above the normal. Specifically, a positive test that is indicative of type 1A (autoimmune) diabetes is one that is three standard deviations above the mean of a substantial number of normals or over the 99th percentile. Your son’s doctor can explain what this means. The other issue in antibody testing is that you need to test for more than one antibody before dismissing the test as a negative one. It is now routine to look at levels of anti-GAD, ICA 512 and anti-insulin antibodies because the likelihood of developing clinical diabetes depends on whether one or three tests are truly positive. Quest Diagnostics is one of a number of laboratories that report these tests correctly. If indeed all three tests are clearly not in the autoimmune range then other possibilities such as type 1B diabetes, the MODYs and type 2 diabetes need to be considered, always remembering that what is important is control of the blood sugar rather than the specific diagnosis which is anyway likely to be clearer with time.

DOB