The two primary tests

There are two specific glucose tests for the diagnosis of diabetes. But since high blood sugar level can depend on other factors as well, doctors, along with the test results, also consider the classic symptoms of diabetes and medical history. The two main tests are:

1) Fasting Blood Glucose Test: For people with many symptoms, "fasting glucose" is the standard test used most often to diagnose diabetes. You'll be tested in the morning, so you shouldn't eat anything after dinner the night before. A value of 126 mg/dl and above on at least two occasions typically means a person has diabetes (Normal fasting blood sugar is less than 100 mg/dL) A value of 110-125 mg/dl is called impaired fasting glucose level. This could be a sign of prediabetes, which means that you have a high risk of getting diabetes in the future.

2) The Oral Glucose Tolerance Test: This is a test to determine how the body handles the excess glucose administered to it after fasting for at least 10 hours (but less than 16 hours). The initial blood sugar reading is taken and then the person is given a high amount of glucose (75 grams), (or 100 grams for pregnant women).

This test is applicable only if the patient is active and in good health (No other illness or on any medication which could affect glucose level). Usually only 2-hr blood sample is taken. If the blood glucose level at 2 hours is 200 mg/dl or more on at least two occasions, it indicates diabetes.

A value of 140-200 mg/dl is called impaired glucose tolerance, a sign of prediabetes. This is also considered a risk factor for future diabetes.

Measurement of the fasting plasma glucose level is the preferred diagnostic test, but any combination of two abnormal test results can be used. Fasting plasma glucose was selected as the primary diagnostic test because it predicts adverse long-term complications (e.g., retinopathy) and can be readily incorporated with fasting lipid determinations.

Identifying prediabetics earlier in the disease process will help in earlier lifestyle changes and medical treatment that can decrease the complications of this condition.