DefinitionA CSF glucose test measures the amount of sugar (glucose) in the cerebrospinal fluid (CSF). CSF is a clear fluid that flows in the space surrounding the spinal cord and brain.See also:Glucose test - bloodGlucose test - urineAlternative NamesGlucose test - CSF; Cerebrospinal fluid glucose testHow the test is performedA sample of CSF is needed. A lumbar puncture, also called a spinal tap, is the most common way to collect this sample. For information on this procedure, see the article on lumbar puncture.Other methods for collecting CSF are rarely used, but may be recommended in some cases. They include:Cisternal punctureVentricular punctureRemoval of CSF from a tube that is already in the CSF, such as a shunt or ventricular drainAfter the sample is taken, it is sent to a laboratory