Diabetes is a disease in which our bodies do not produce enough insulin or effective insulin. Most of the components of our meal contain sugar. When we eat food, it is broken down into simple sugar called glucose. This glucose is taken by blood and it travels there freely till it is used by the cells to produce energy. Our cells use glucose to produce energy to do work such as our daily activities of walking, sitting, running and so on.

Diagnosis of Diabetes

A fasting plasma glucose (FPG) test measures blood glucose in a person who has not eaten anything for at least 8 hours. This test is used to detect diabetes and pre-diabetes. The FPG test is most reliable when done in the morning. Fasting Blood Glucose Test is convenient and has low cost. However, it sometimes misses diabetes or pre- diabetes and has to be confirmed with the OGTT. People with a fasting glucose level of 100 to 125 milligrams per deciliter (mg/dL) have a form of pre-diabetes called impaired fasting glucose (IFG). Having IFG means a person has an increased risk of developing type 2 diabetes but does not have it yet. A level of 126 mg/dL or above, confirmed by repeating the test on another day, means a person has diabetes.

An oral glucose tolerance test (OGTT) measures blood glucose after a person fasts at least 8 hours and 2 hours after the person drinks a glucose-containing beverage. This test can be used to diagnose diabetes and pre-diabetes. Research has shown that the OGTT is more sensitive than the FPG test for diagnosing pre-diabetes, but it is less convenient to administer. The OGTT requires fasting for at least 8 hours before the test. The plasma glucose level is measured immediately before and 2 hours after a person drinks a liquid containing 75 grams of glucose dissolved in water. If the blood glucose level is between 140 and 199 mg/dL 2 hours after drinking the liquid, the person has a form of pre-diabetes called impaired glucose tolerance (IGT). Having IGT, like having IFG, means a person has an increased risk of developing type 2 diabetes but does not have it yet. A 2-hour glucose level of 200 mg/dL or above, confirmed by repeating the test on another day, means a person has diabetes.

A random plasma glucose test, also called a casual plasma glucose test, measures blood glucose without regard to when the person being tested last ate. This test, along with an assessment of symptoms, is used to diagnose diabetes but not pre-diabetes. Test results indicating that a person has diabetes should be confirmed with a second test on a different day. Other symptoms can include fatigue, blurred vision, increased hunger, and sores that do not heal. The doctor will check the person’s blood glucose level on another day using the FPG test or the OGTT to confirm the diagnosis.