Diagnosing Diabetes – Not All Tests are the Same!

There are few things which confuse people more than knowing when and if they have diabetes, and what tests they should take in order to get this confirmation. And it’s reasonable to be confused. There is a lot of misinformation and ignorance when it comes to identifying diabetes – even within the medical community.

I’ll never forget the year when I was diagnosed. It was midsummer in 2009, and I hadn’t been feeling well, so I decided out of concern, to order a glucose meter and strips. This – because my own father had diabetes, and since I have Polycystic Ovarian Syndrome, I had been warned many years prior that I ought to keep an eye on my blood sugars because the condition could lead to it. But nothing more was said. At the time, I was not super knowledgeable about where the boundaries lay… but I suspected 156 mg/dL, three hours after a meal, was not normal. So I went in to see my doctor. She assured me that that was normal. I had this gut feeling that she was wrong; that she was dismissive. But I didn’t have the knowledge to confront her, and I thought she knew something I didn’t.

Two months later, I developed a yeast infection which would not go away. The LPN nurse who examined me, after many failed attempts at curing this, decided to do a glucose in urine test. I failed this test, was referred back to my doctor, and was finally sent for an HbA1c test which came back at 10.5%. My average blood glucose had been at 255 mg/dL. That afternoon, while we were putting up the Christmas tree, I passed out from high blood sugar.

My doctor expressly apologized to me for her incompetence and pledged to go learn more from the American Diabetes Association website. I don’t know about you – but that scared me stiff. And this is not uncommon. It is NOT uncommon for many doctors, nurses, registered dietitians, etc., to not be very knowledgeable about diabetes, despite the seriousness of the condition and its steady rise in incidence. It is misguided to think that there’s nothing to worry about, unless a person’s fasting glucose is above 200 mg/dL.

Tests for diabetes

Many may also give the WRONG test, and then dismiss the patient as not having diabetes. But not all tests are made the same. Here’s a run-down of a few tests you might see:

Fasting blood glucose

This is a test often given to someone on an empty stomach – usually 12 hours. If a person’s glucose has been high for a while, it can be a good indicator that more testing needs to be done. But this may not always reflect that there is high glucose impairment, so it is not the only test that should be done. It is merely a small snapshot of a glucose level. Any reading above 100 mg/dL is abnormal or prediabetic, and any reading above 126 mg/dL is considered a sign of diabetes.

Urine in glucose

Like the fasting blood glucose, this test can be done to gauge if a person is already releasing excessive glucose in their urine, and might have diabetes. It alone, is not a diagnosis tool. It is generally performed for pregnant women, or after chronic yeast or urine infections. Anything above 0.8 mmol/L is a sign of concern.

GTT (Glucose Tolerance Test)

This is a test in which a person is given a glucose solution to drink, on an empty stomach. The solution can be 50-75 mg of pure glucose. A patient’s blood glucose will then be tested at 2 hours, and sometimes 3 hours, to determine the rise of their blood glucose as a reaction to the solution. If at 2 hours, glucose is between 140-199 mg/dL, it is considered impaired. If it’s above 199 mg/dL, it is considered diabetic. This test is a good for any person who is prediabetic because they may not always have high blood glucose, on average, and this impairment might be missed in other tests, which are more meant to capture consistent and chronically high blood glucose. This is a mandatory test for pregnancy, during the third trimester.

HbA1c (Glycated Hemoglobin Percentage)

The HbA1c percentage measures how much sugar is attached to the blood’s hemoglobin protein. It’s like taking a snapshot of where a patient’s blood glucose levels have been for the last 2-3 months. For this reason, and because the patient does not have to ingest any solutions, it is a great diabetes management tool. If a patient’s average blood glucose has been above 140, it will easily reflect on HbA1c (or A1C) test. If a doctor has reason to believe a patient has had chronically high blood glucose levels for an extended amount of time (such as with a failed fasting glucose or a failed urine glucose test), then an A1C is the right tool. However an A1C which is low enough that a person seems to be prediabetic should always be followed by a GTT, in order to determine that this person is, in fact, prediabetic and not diabetic. Unfortunately many patients are misdiagnosed – or wrongly told they are fine or have no diabetes – because of failure to follow up with this.

At the end of the day, YOU are the captain of your own health. If you are unsure about your diabetes diagnosis, ask for further or more specific testing. If someone denies you testing, seek a different medical opinion. It is YOUR right to be tested and to rule out diabetes.

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