The Glucose CSF test is a critical, specialized test performed in an emergency setting. It measures the amount of glucose in your cerebrospinal fluid (CSF)—the fluid surrounding your brain and spinal cord. It is essential for diagnosing serious central nervous system infections like bacterial meningitis. In these cases, bacteria consume the glucose, causing CSF levels to drop. The sample is collected via a lumbar puncture (spinal tap). This is a vital diagnostic tool used by doctors to rapidly identify life-threatening infections.