Fasting Plasma Glucose Test

A fasting plasma glucose test is performed after the patient has gone at least 12 hours without food or drink (except for water). Like the random plasma glucose test, it is performed by having a blood test and having the Blood glucose levels analyzed by a laboratory.

What makes the fasting plasma glucose test different from the random plasma glucose test is that through fasting the body of a person without diabetes will produce and process insulin in response to increased glucose in the blood. For a person with diabetes, the body will not have that same response and their blood glucose levels will remain high. Receiving two readings of blood glucose levels of 140 mg/dl or over usually means the person has diabetes. A normal level for a person without diabetes should be in the 70-110 mg/dl range after fasting.