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Glucose and Diabetes
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Currently under review
Pending specialist review and validation.
The Glucose CSF test measures the amount of glucose, a form of sugar, in the fluid that surrounds your brain and spinal cord. This fluid, called cerebrospinal fluid, cushions the central nervous system and reflects what is happening within and around it.
A small sample of cerebrospinal fluid is collected through a lumbar puncture. CSF glucose helps your care team evaluate how well glucose is moving from your blood into the CSF and how it is being used within the central nervous system, in context with your symptoms and other CSF tests.
CSF glucose is commonly checked when your clinician suspects infections of the brain or spinal cord, such as meningitis, or other conditions that affect the meninges or brain metabolism. Certain infections, cancers, and inflammatory diseases can lower CSF glucose, while high CSF glucose usually reflects elevated blood glucose.
Doctors interpret CSF glucose together with blood glucose measured near the time of the lumbar puncture, as well as CSF cell counts, protein, culture, and other studies. The pattern can help distinguish among causes of headache, fever, neck stiffness, altered thinking, seizures, or other neurologic symptoms, and guide urgent treatment decisions.
Your result is interpreted alongside a blood glucose level taken close to the time of your lumbar puncture and with other CSF findings. A lower than expected CSF glucose may point toward certain infections or inflammatory or malignant conditions, while a higher value often mirrors high blood glucose. By itself, the number does not make a diagnosis.
If your result does not fit your symptoms, your clinician may repeat or confirm testing, review how the sample was collected and transported, and order additional studies such as cultures, viral tests, imaging, or repeat blood work. Treatment and follow up are based on the overall clinical picture and how you are doing, not just a single laboratory value.
Reference intervals vary by laboratory, analyzer, methodology, population, and units. The ranges shown here are for education only. Always interpret your results against the reference interval printed on your own lab report.
CSF glucose largely reflects your blood glucose. Recent meals, diabetes control, insulin dosing, or IV dextrose can raise or lower blood glucose and, in turn, influence CSF glucose. A paired blood sample helps with accurate interpretation.
Cells in CSF continue to use glucose after collection. Delays in transporting or analyzing the sample, or not using a glycolysis inhibitor when indicated, can falsely lower the measured CSF glucose.
Insulin, corticosteroids, parenteral nutrition, and IV dextrose can alter blood glucose and indirectly affect CSF glucose. Let your care team know about recent doses and infusions before and during the lumbar puncture.
Heavy blood contamination of the CSF sample may change the measured glucose and complicate interpretation. Laboratories usually note sample appearance and may adjust interpretation accordingly.
Infants, people with diabetes, and those with disorders affecting the blood–brain barrier may have different CSF glucose patterns. Your clinician will interpret results with age, medical history, and other test results in mind.
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