A blood glucose test measures the amount of sugar in your blood at the time of the draw. It is used to screen for and manage diabetes. Here is how to read a fasting result.
Glucose is the main sugar in your blood and your body's primary source of energy. A blood glucose test measures how much is present, and it is often part of a basic or comprehensive metabolic panel. Results depend heavily on when you last ate, so the test is frequently done fasting.
For a fasting sample, a level of 99 mg/dL or below is generally normal, 100 to 125 mg/dL falls in the prediabetes range, and 126 mg/dL or higher on more than one test points toward diabetes. Non-fasting or random tests use different cut-offs, which is why context matters and your clinician interprets the value.
A high glucose can reflect diabetes, recent food, illness, stress, or certain medicines. A low glucose can cause shakiness, sweating, or confusion and has its own causes. One reading is a snapshot; your clinician may repeat it or add an A1c to see the fuller picture.
Upload your metabolic panel and Mednex reads your glucose in plain language, alongside A1c if it is on the report, and tracks the trend.
Decode my labsContent last reviewed 9 July 2026. Reference ranges vary by laboratory; always read your results against the range printed on your own report.
This page explains a common lab marker in general terms using public information from the U.S. National Library of Medicine and other NIH sources. It is educational and is not a diagnosis or medical advice. Reference ranges differ between laboratories and the meaning of a result depends on your age, sex, medications, and overall health. Always discuss your own results with the clinician who ordered them.