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How can an glucose tolerance test help diagnose an insulinoma?

I'm having a hard time with my symptoms. Through diet, I have been able to get my sugar levels up to 80 to 90. My fasting blood glucose levels are between 75 to 85.

My body is still producing too much insulin. Sometimes my blood glucose levels decrease.

For example

Prior to meal 85
1 hour after meal 79
2 hours after meal 86

Most of my meals I do not experience a fluctuation of greater than 10 points in a two hour period. I rarely ever go over 100.

My c-peptides levels have come back high. I repeated the test. Therefore, my body is producing too much insulin.

My endo asked me if I want to do a 4 hour glucose tolerance test. She says it will help rule out an insulinoma. What would the test results be to show an insulinoma as opposed to reactive hypoglycemia. I'm not looking forward to the test.
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replied September 2nd, 2013

First of all, I would suggest to do as your doctor is asking you to as she knows better your entire medical history as we do lack it.

Next, during the glucose tolerance test, after giving a sweet drink, your blood glucose level is measured. Normally, the glucose will raise slightly over the higher limit within the first hour; then, it will go back to normal levels within the other 3 hours.

In case of insulinomas, the blood sugar will fall down sharply (more than normal) and would not get to the level as normally happening.

There is another test to measure insulin and glucose levels and their ratio to determine insulinoma.

As you may see, the diagnosis is difficult and needs patience.

Hope it helped!

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