QUESTION:
What effect does a seizure have on blood glucose levels?
Quick Answer
A seizure may temporarily raise blood glucose because stress hormones stimulate the liver to release glucose, but this does not happen after every seizure and the increase is often modest and short-lived. Glucose may instead be low if hypoglycemia caused the seizure, or very high if a hyperglycemic emergency contributed to it. A glucose reading taken after a seizure therefore cannot show by itself whether glucose was the cause or the result. Check glucose immediately, treat a confirmed low without delay and seek urgent medical assessment for a first, prolonged or unexplained seizure.
Answer by Dr. Albana Greca, MD, MMedSc
Hello,
Abnormal glucose can provoke a seizure, while a seizure can temporarily alter glucose. Timing and circumstances matter.
Yes, sometimes. A convulsive seizure raises stress hormones that may make the liver release glucose, causing temporary stress hyperglycemia.
The rise may be mild, absent or occasionally pronounced, especially after prolonged seizures or serious illness, and usually settles during recovery.
Not every seizure raises glucose. Repeat a high reading and interpret it with HbA1c, previous values and the cause.
Yes. Severe hypoglycemia can cause confusion, abnormal behavior, unconsciousness, seizure, coma or death.
Below 70 mg/dL is low and below 54 mg/dL is clinically significant. Severe hypoglycemia means altered function requiring another person’s help, regardless of the number.
Risk is highest with insulin or sulfonylureas, especially after missed meals, excess doses, alcohol or kidney decline. See our low blood sugar guide.
During a seizure or unconsciousness: Give nothing by mouth. Use glucagon if available, call emergency services, protect the person from injury and place them on their side when possible.
It can. HHS or severe nonketotic hyperglycemia may cause seizures with dehydration and metabolic disturbance. Seizures may be focal or generalized.
DKA can also cause altered consciousness and, less commonly, seizures through severe metabolic disturbance or another illness.
Very high glucose with confusion, dehydration, vomiting, deep breathing or seizure is an emergency. See our severe hyperglycemia guide.
A glucose of 180 mg/dL after a seizure may mean:
Document when glucose was checked and whether treatment was given. HbA1c helps distinguish chronic hyperglycemia from stress response.
Syncope is not the brain “stopping.” It is brief unconsciousness from temporarily reduced brain blood flow, often due to low pressure or a heart-rhythm problem.
Brief jerking can occur during fainting. Witness details, recovery time, tongue injury, ECG and sometimes EEG help distinguish syncope from seizure.
A new seizure requires assessment for metabolic, cardiac, infectious, medication-related and structural causes—not only epilepsy.
A temporary high does not diagnose diabetes. Repeat fasting glucose or HbA1c may be needed. See our testing guide.
Call emergency services for a first seizure, a seizure lasting five minutes or longer, repeated seizures without recovery, breathing difficulty, serious injury, pregnancy, a seizure in water, persistent confusion, one-sided weakness, very low glucose that does not respond, or very high glucose with dehydration or ketones.
People at risk of severe lows should keep glucagon available and train close contacts. See our insulin safety guide.
This answer does not determine an individual seizure’s cause or replace emergency care.
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