>

Blood Glucose Tests: Types, Purposes and Approaches

High blood sugar means that your are on your way to diabetes or may already have it. However, the condition can be reversed. The earlier you take action the greater the chance to get back to healthy blood sugar levels.

Read about reversing high blood sugar safely   >>>

There are numerous approaches to blood glucose testing. The test recommended by your healthcare provider depends on your personal case and the purpose of testing. For example, some tests are done in order to diagnose diabetes, some help you monitor and control your blood sugar, insulin or other medication administration The common types of blood glucose tests are:

  • fasting test
  • two-hour postprandial test
  • oral glucose tolerance test
  • hemoglobin A1c
  • random

Fasting blood glucose test

Fasting blood sugar test is one of the most accurate and important tests in diagnosing diabetes or pre-diabetes. You should be fasting for at least 8-10 hours before doing this type of test. This means not eating anything at all and drinking only water. For this reason, the test is usually taken early in the moring on an empty stomach. This test shows your lowest glucose levels as they are not affected by recent meals.

The normal level should be under 100mg/dL or 0.01% concenrtation or less than 5.5 mmol/L. If your test result is higher than 100mg/dL, extra tests are recommened:

  • for the reading between 100mg/dL and 125mg/dL, extra blood sugar tests comfirm pre-diabetes or diabetes
  • for readings higher than 125mg/dL they confirm diabetes.
  • if you don't have diabetes symptoms and the test resuls are higher than 7.0 mmol/L or more , extra tests are recommened
  • if you have diabetes symptoms and the test resuls are higher than 7.0 mmol/L or more , extra tests are unnecessary to confirm diabetes

Postprandial Glucose Test (PPG)

Postprandial test is used to measure blood plasma glucose 2 hours after meals. The time is counted from the moment a person starts taking meal. In most general words, this type of test shows how quickly and effectively your body cells absorb glucose from your blood or show how tolerant the body is to glucose.

Glucose levels in our blood reach peak levels approxomately 1 hour after meal. After that, sugar levels in healthy a person's blood start to lower and should return to preprandial levels within 2–3 hours after meals. In diabetic persons, these timeframes are altered.

IDF guidelines for interpreting PPG results are the following:

  • below 3.9 mmol/l (70 mg/dL) - too low, may point to reacitve reactive hypoglycemia
  • under 7.8 mmol/l (140 mg/dl) - normal
  • between 7.8 and 11.1 mmol/l (140 and 200 mg/dl) - impaired glucose tolerance:
  • equal or above 11.1 mmol/l (200 mg/dl) - Diabetes

However, unlike fasting blood glucose test, this type of test does not diagnose diabets and American Diabetes Association does not recommend using PPG for this pursose. One of the reasons for that is that PPG test resutls may be affected by medications, taken by a person, foods eaten 2 hours before the test, peciliarities of one's diet or recent illnesses. All these factors should be taken into account while interpreting test results. In order to mitigate interference of food factor and peculiarities of a person's diet, UK doctors use a stricter version of PPG - Oral Glucose Tolerance Test. For tesing results, a certain amount of glucose (75g according to International Diabetes Federation standards) and glucose is measured 2 hours after that.

A PPG test can only confirm postprandial hyperglycemia, reactive hypoglycemia or impaired glucose tolerance. However, being aware of PPG is important becuase, according to the International Diabetes Federation, elevated PPG levels form a risk factor for macrovascular disease.

Oral glucose tolerance test (OGTT)

Like Postprandial test, oral glucose tolerance testestimates one's ability to metabolize glucose. Unlike it is with postprandial test, OGTT is performed after the patient takes a cartain amount of glucose. This is the only test that confirms IGT with certainty.

The time ranges and glucose amount vary for different patient groups:

  • In adults, the test in performed 2 hours after taking 8 ounce with 75g of sugar
  • In childred, the test in performed 2 hours after taking 1.75g of sugar per kilo of body weight
  • In pregnant women, the test is performed 1,2 and 3 hours after taking 8 ounce solution with 100g of sugar

Fasting 8 to 12 hours before the test is required, water can be drunk in small amounts.

Hemoglobin A1c test

The hemoglobin A1C or HbA1c, or just A1c test test is used to measure one's average blood sugar over the period of 3 months. Along with fasting blood sugar test, this test is used to diagnose diabetes and prediabetes. In addition, this test helps manage and control diabetes, estimate efficacy of the chosen therapy.

The working principle of the A1C test is based on the attachment of glucose to hemoglobin and the test results are measured in percentage. The percentage figure shows the amount of hemoglobin with glucose attached to it.

Interpreting A1c results:

  • Below 5.7% - Normal
  • 5.7% to 6.4% - Prediabetes
  • 6.5% or above - Diabetes

Fasting is not necessary before an A1c test, your can eat and drink normally. However, test resutls may be misleading in people who have conditions or diseases diseases affecting thier hemoglobin, for example, blood loss or iron deficiency.

Random blood sugar test (RBS)

Random glucose tests check the levels blood glucose at any given moment during the day. Even being simple and minimally invasive, the test is still taken at outpatient facilities as the process required venous access. In addition, a workout of other physical activities before an RBS test can also cause inaccurate results.

The reading should not exceed 200 mg/d, otherwise diabetes is diagnosed.

Taking a random blood glucose test does not require fasting or other special preparations. More than that, the test is often used in urgency situations, for instance, when a person needs an unplanned surgery.

High blood sugar means that your are on your way to diabetes or may already have it. However, the condition can be reversed. The earlier you take action the greater the chance to get back to healthy blood sugar levels.

Read about reversing high blood sugar safely   >>>

Glucose Health Basics: