Important Tests Needed By People with Diabetes - P1

Diagnosis of diabetes for type 2 is often a sticky topic in the last few years. This is very true for all types of diabetes. Too often physicians make assumptions that are not correct. They look at a person, the age, and often do one of the required tests. Often they are correct, but what a disappointment for those that are incorrectly diagnosed. Even the American Diabetes Association makes mistakes and this one could be very large.

There are tests for screening, tests for diagnosis, tests for monitoring, tests to evaluate glucose levels, and tests for the complications of diabetes. Read this blog as well by Joslin Diabetes Center about tests for diagnosis.

The tests for screening and/or to diagnose pre-diabetes and diabetes can be used as part of a regular physical, when a patient has symptoms suggesting diabetes, when a patient has a condition that is associated with diabetes, and when a patient presents to the emergency room with an acute condition.

Screening tests generally include:

1. Fasting glucose (fasting blood glucose, FBG) – this test measures the level of glucose in the blood after an 8-12 hour fast. Also fasting plasma glucose (FPG).
2. A1c (also called hemoglobin A1c or glycohemoglobin) – this test evaluates the average amount of glucose in the blood over the last 2 to 3 months and has been recommended more recently as another test to screen for diabetes.
3. Sometimes a random blood glucose level is used for screening when a fasting test is not possible, such as when a person is seriously ill.
4. Sometimes random urine samples are tested for glucose, protein, and ketones during a physical. If glucose and/or protein or ketones are present on the indicator strip dipped in the urine sample, the person has a problem that needs to be addressed. This is a screening tool, but it is not sensitive enough for diagnosis or monitoring.

If you trust the American Diabetes Association (ADA), they promote first the A1c test, then the FPG and finally the oral glucose tolerance test. You must use care with all tests and know the limitations of each.

1. The FBG requires an 8-hour fast.
2. The OGTT requires that the person have a fasting glucose test, followed by the person drinking a standard amount of glucose solution to "challenge" their system, followed by another glucose test 2 hours later.
3. With the A1c, people do not have to fast for 8 hours or endure multiple blood samples being taken over several hours, but the test is not recommended for everyone. It should not be used for diabetes diagnosis in people who have had recent severe bleeding or blood transfusions, those with chronic kidney or liver disease, and people with blood disorders such as iron-deficiency anemia, vitamin B12 anemia, and hemoglobin variants. In addition, only A1c tests that have been referenced to an accepted laboratory method (standardized) should be used for diagnostic or screening purposes. Currently, point-of-care tests, such as those that may be used at a doctor’s office or a patient’s bedside, are too variable for use in diagnosis but can be used to monitor treatment (lifestyle and drug therapies). Also, the A1c is of questionable value in diagnosis of young people (read this).

If the initial result from one of the above tests is abnormal, the test should be repeated on another day to confirm a diagnosis of diabetes. Once the diagnosis had been made then it may be wise to have the diabetes autoantibodies test, which should help distinguish between type 1 and type 2 diabetes if the diagnosis is unclear. The presence of one or more of these antibodies indicates type 1 diabetes.

Now for pre-diabetes and diabetes, the guidelines are as follows: The A1c test can be used to either monitor diabetes treatment in a person that has diabetes or to screen for and diagnose diabetes and prediabetes. An A1c of less than 5.7% is not diabetes, an A1c of 5.7% to 6.4% says prediabetes, and an A1c of greater than 6.4% is diabetes.

Some doctors use the fasting plasma glucose (FPG) test and the A1c to make a diagnosis. The FPG reading of less than 100 mg/dl (5.6 mmol/L) means no diabetes, a FPG reading of 100 to 125 mg/dl (5.6 to 6.9 mmol/L) is prediabetes, and a FPG reading greater than 125 mg/dl (6.9 mmol/L) is diabetes.

Others also add the oral glucose tolerance test (OGTT). This requires the person to drink a 75-gram glucose drink. At the two-hour mark a blood sample is drawn. If the results are less than 140 mg/dl (7.8 mmol/L) then you do not have diabetes or prediabetes. If the results are from 140 to 200 mg/dl (7.8 to 11.1 mmol/L) it is considered prediabetes. If the results are over 200 mg/dl (11.1 mmol/L) then the diagnosis is diabetes.

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