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From Southeastern Colorado, USA:

Should I discount all my meter readings, since they did not "agree" with the laboratory numbers?

I am 27, female, thin, normal cholesterol and blood pressure, but I seem to have a few symptoms of diabetes, including thirst/very dry throat, constant hunger, and more frequent urination. I have been monitoring my blood sugars for one and a half months. My blood sugars have ranged from 65 to 290 mg/dl [3.6 to 16.1 mmol/L]. I've had very frequent numbers over 200 mg/dl [11.1 mmol/L] following lunch and dinner. All fasting blood sugars have been normal. I have charted all numbers and there is a definite high pattern following afternoon meals. I have verified high readings with two other meters and re-washed hands many times; I was still high.

I went to an endocrinologist who ordered an antibody test, which came back normal, and an OGTT. I as 84 mg/dl [4.7 mmol/L] fasting; 140 mg/dl [7.8 mmol/L] at one hour; and 113 mg/dl [6.3 mmol/L] at two hours. I also tested with all three of my meters and they all were within 15 point agreement at every check. The meters said I was 88 mg/dl [4.9 mmol/L] fasting; 190 mg/dl [10.6 mmol/L] at 30 minutes; 180 mg/dl [10.0 mmol/L] at one hour; and 140 mg/dl [7.8 mmol/L] at two hours. They obviously don't match up. The endocrinologist said all my meter readings from the past are false! He said that meters do not work for me and that the laboratory says I am normal and that is all he has to say. Is it possible that the three meters are all so wrong and that I am normal? Last month, I had an OGTT. At one hour, I was 109 mg/dl [6.1 mmol/L] and at two hours, I was 103 mg/dl [5.7 mmol/L]. I asked if it was significant that the number had gone up so much in a month and he said no. Is that true?


Glucose meters are not meant to take the place of the laboratory tests ordered by your physician on blood drawn from an arm vein. There is much more precision in that measurement. The FDA, when they approve glucose meters for sale in the U.S., allows a 20% error in their measurements. That means they are not precise instruments for measuring glucose. However, they are good enough to follow if you have to measure daily and can be used to make treatment decisions for treating diabetes. I would say that with two OGTT tests normal, you can relax about diabetes. However, I would continue to work on lifestyle choices of diet and exercise to decrease your risk over time.


Original posting 17 Apr 2006
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