Fasting Blood Glucose (FBG) Test

Fasting Blood Glucose measures the amount of sugar circulating in your bloodstream after you've gone without food or drink (other than water) for at least eight hours.

In a healthy person, insulin keeps blood glucose within a fairly narrow, stable range even after a period of fasting, so an elevated fasting glucose level is one of the earliest and most reliable signs that the body's ability to regulate blood sugar has been impaired.

This test remains one of the primary tools for diagnosing diabetes and prediabetes, alongside HbA1c and the oral glucose tolerance test, and it's simple, quick, and widely available.

Because untreated high blood sugar can silently damage blood vessels, nerves, and organs over years, regular fasting glucose screening is a cornerstone of preventive health care, especially for adults with risk factors for diabetes.