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February 18, 2008

A1c (Glycohemoglobin, HgbA1c)

Question from Bermuda:

My 15-year-old daughter was diagnosed with type 1 at age 11. Last month, her A1c was 17. What could be the cause of such a high reading? I see her test herself and give her insulin after her meals. She has not been having any highs or lows and her readings have been between 70 mg/dl [3.9 mmol/L] to 220 mg/dl [12.2 mmol/L]. She takes 16 units of long lasting insulin at about 7 a.m. each morning and 36 units of the same in the evening at about 8:30 p.m. and I don't always watch her. The amount of insulin she takes during the day depends on the carbohydrates she eats and, unfortunately, since I'm not at school with her, I can't control what she does at lunch time. She currently takes one unit of insulin to 15 grams of carbohydrates. She tests her sugar before she eats and administers insulin after eating. She was recently equipped with a CGMS. I got the results yesterday that said after breakfast she is high, up to 400 mg/dl [22.2 mmol/L]. The diabetes nurse has suggested she change her breakfast insulin to 1:12 instead of 1:15.


Excuse any tone that seems like being “too blunt” here. What causes an A1c of 17% in a patient with diabetes? Poor glucose control, specifically, glucose readings in the 400s mg/dl [over 22.2 mmol/L].

Okay, let’s take a step back. The hemoglobin A1c test is influenced by several factors, especially your hemoglobin quality/quantity and your glucose concentrations. One can get a falsely high (or low) A1c. After all, no test is always perfect, especially if one has an irregular hemoglobin, such as sickle cell hemoglobin. But then, one would expect ALL the A1cs NEVER to have been right and the tone of your letter suggests that this recent A1c of 17% was unexpected.

You see her test and give insulin, but you recognize that you cannot always watch her. DO YOU PARTICIPATE? Do you oversee and check her meter to be certain what the glucose values are? Do you help her count carbohydrates and calculate the insulin doses? I suspect that you don’t. Many parents begin to slack off on this as their diabetic children reach their teens. But, this is probably the time for even greater scrutiny.

All of this, then, implies that their could be degrees of deception here. So, you and your daughter and your diabetes team need to ask “Why?” What is to be gained by any deception? Does the girl feel that if she doesn’t give the “answers we want” that she will be punished? Is she inwardly wanting her glucose levels to be high to help control her weight?

I fear that you have only touched the tip of the iceberg. Talk with your diabetes team about how they think you should proceed.


[Editor’s comment: When you discuss this situation with your daughter’s diabetes team, you may wish to ask them about the timing of her insulin shots, especially those at meal time. To have lower postprandial blood sugars, she should be giving her mealtime insulin BEFORE she eats, especially if her pre-meal blood sugar is high.