A Fasting Plasma Glucose (FPG) test is a common blood test that measures your blood sugar levels after a period of fasting (not eating or drinking anything except water). It is a simple, accurate, and inexpensive test that can screen for diabetes and prediabetes. Normal FPG levels: 70-99 mg/dL (3.9-5.5 mmol/L) Prediabetes FPG levels: 100-125 mg/dL (5.6-6.9 mmol/L) Diabetes FPG levels: 126 mg/dL (7.0 mmol/L) or higher on two separate tests If your FPG level is high, your doctor may recommend additional tests to confirm a diagnosis of diabetes or prediabetes. These tests may include an oral glucose tolerance test (OGTT) or an A1C test. It is important to note that FPG levels can be affected by certain medications, medical conditions, and stress. If you have any concerns about your FPG level, talk to your doctor.