Diabetes can cause seizures, though the connection is not straightforward
Yes, diabetes can lead to seizures, but it usually happens through one of two separate pathways rather than directly. The first is severe low blood sugar (hypoglycemia), which starves the brain of glucose and can trigger a seizure within minutes. The second is diabetic ketoacidosis or hyperosmolar hyperglycemic state — dangerous conditions where blood sugar climbs so high that the body's chemistry becomes severely imbalanced. Both situations are medical emergencies. A person with diabetes can also have seizures unrelated to their diabetes entirely, which is why a seizure always warrants a call to 911 or a trip to the emergency room.
Understanding which pathway led to a seizure matters because the treatment is different. Low blood sugar requires immediate glucose; high blood sugar emergencies require insulin and fluids in a hospital setting. In the emergency room, doctors will test for all possibilities rather than assuming the seizure is diabetes-related.
Key Takeaways
- Severe low blood sugar can cause seizures within minutes because the brain cannot function without adequate glucose.
- Diabetic ketoacidosis and hyperosmolar hyperglycemic state — both caused by dangerously high blood sugar — can also trigger seizures and require emergency care.
- A seizure in someone with diabetes is a medical emergency; call 911 rather than assuming it is diabetes-related.
- Keeping blood sugar within your target range, recognizing early warning signs of low blood sugar, and having a treatment plan reduce seizure risk.
How severe low blood sugar causes seizures
The brain runs almost entirely on glucose, the sugar that comes from food and is regulated by insulin. When blood sugar drops below roughly 40 mg/dL — a state called severe hypoglycemia — the brain does not have enough fuel to function normally. Neurons begin to misfire, and a seizure can result.
This happens fastest in people taking insulin or certain diabetes medications that force the body to produce more insulin. If someone takes their usual dose but eats less than planned, skips a meal, exercises harder than expected, or drinks alcohol without food, blood sugar can plummet. The person may feel shaky, sweaty, or confused at first, but if blood sugar continues to fall, a seizure can occur before they realize what is happening.
The seizure itself is the brain's distress signal — it is not the diabetes itself causing harm, but the lack of fuel. Once blood sugar is raised back to normal (usually with glucose tablets, juice, or an injection of glucagon), the seizure stops and the brain recovers. However, repeated severe low blood sugar episodes can damage the brain over time, which is why prevention is critical.
Diabetic ketoacidosis and high blood sugar emergencies
Diabetic ketoacidosis (DKA) occurs when blood sugar becomes extremely high and the body cannot use it effectively. This happens most often in people with type 1 diabetes when insulin is missing or insufficient. The body then breaks down fat for energy, producing acids called ketones that accumulate in the blood and make it dangerously acidic. This chemical imbalance can cause seizures, along with confusion, rapid breathing, nausea, and abdominal pain.
A similar but separate emergency called hyperosmolar hyperglycemic state (HHS) occurs mainly in type 2 diabetes when blood sugar climbs extremely high — sometimes above 600 mg/dL — without enough ketone buildup to trigger DKA. The blood becomes so concentrated that cells shrivel, and the brain can swell. Seizures, confusion, and loss of consciousness can follow.
Both conditions develop over hours to days, not minutes. Early warning signs include persistent thirst, frequent urination, fatigue, blurred vision, and fruity-smelling breath (in DKA). If you notice these signs, contact your doctor or go to the emergency room immediately. Do not wait for a seizure to occur.
Why a seizure in someone with diabetes is always an emergency
A seizure is a medical emergency regardless of whether someone has diabetes. Call 911 immediately if you witness a seizure or experience one yourself. Do not assume it is caused by blood sugar, even if the person has diabetes — seizures can result from stroke, infection, head injury, or other conditions unrelated to diabetes.
In the emergency room, doctors will check blood sugar first, but they will also run other tests to rule out other causes. They may order a CT scan or MRI of the brain, blood tests to check kidney and liver function, and an electroencephalogram (EEG) to measure brain activity. This thorough approach is necessary because the treatment depends on the actual cause.
If the seizure was caused by low blood sugar, treatment is straightforward: raise blood sugar and monitor it closely. If it was caused by DKA or HHS, treatment involves insulin, fluids, and electrolyte replacement in an intensive care setting. If another cause is found, treatment addresses that condition.
Recognizing early warning signs of dangerous blood sugar levels
Most seizures caused by diabetes are preventable if you catch low or high blood sugar before it becomes severe. Learn to recognize the early signs of low blood sugar: shakiness, sweating, rapid heartbeat, anxiety, hunger, tingling around the mouth, and difficulty concentrating. These symptoms appear before seizure risk becomes high, giving you time to treat.
For high blood sugar, watch for persistent thirst, frequent urination, fatigue, blurred vision, and headache. These develop more slowly than low blood sugar symptoms, but they signal that your blood sugar is drifting into dangerous territory. Keeping a log of when these symptoms occur and what your blood sugar reading was at the time helps you spot patterns and act sooner next time.
If you have diabetes and experience a seizure, or if you have repeated episodes of severe low blood sugar, talk to your doctor about adjusting your medication, meal timing, or exercise routine. Some people benefit from a continuous glucose monitor (CGM), a small device worn on the skin that tracks blood sugar in real time and alerts you when levels are dropping. Others may need to change the type or dose of insulin or other medications they take.
What to do if you have had a seizure related to diabetes
After a seizure caused by low blood sugar, your doctor will want to understand what led to it. Bring a record of your blood sugar readings (from a meter or CGM), your medication doses, what you ate that day, and any unusual activity or stress. This information helps your doctor spot patterns and adjust your treatment plan.
You may also be referred to a diabetes educator or dietitian who can help you recognize early warning signs and adjust your daily routine to prevent future episodes. Some people benefit from learning to use a glucagon emergency kit — an injection that raises blood sugar quickly if someone becomes unconscious or unable to swallow. Family members and close contacts should know where the kit is kept and how to use it.
If seizures continue despite good blood sugar control, your doctor may refer you to a neurologist to investigate other possible causes. Seizure disorders and diabetes can coexist independently, and both conditions need proper treatment.
Frequently Asked Questions
Can high blood sugar alone cause a seizure without DKA or HHS?
Moderately high blood sugar alone does not usually cause seizures. Seizures from high blood sugar typically occur only when blood sugar becomes dangerously high (usually above 400 mg/dL) and the body's chemistry becomes severely imbalanced, as in DKA or HHS. Chronically high blood sugar can damage nerves and blood vessels over years, but it does not trigger acute seizures.
If I have diabetes and a seizure, is it always caused by my blood sugar?
No. Seizures can result from stroke, infection, head injury, medication side effects, or a separate seizure disorder. Having diabetes increases the risk of some of these conditions — for example, diabetes raises stroke risk — but the seizure itself may not be directly caused by blood sugar. This is why emergency evaluation is essential.
Can I prevent seizures if I have diabetes?
Yes, in most cases. Keeping blood sugar within your target range, eating regular meals, taking medications as prescribed, and recognizing early warning signs of low or high blood sugar prevent most diabetes-related seizures. A continuous glucose monitor can alert you to dangerous changes before they become severe. Talk to your doctor about your individual risk and what prevention steps make sense for you.
What should I do if someone with diabetes has a seizure near me?
Call 911 immediately. Do not try to force anything into their mouth or restrain them. Turn them on their side to keep their airway clear, and stay with them until help arrives. Let paramedics know the person has diabetes and whether you know their recent blood sugar readings. Do not assume the seizure is caused by blood sugar — emergency responders need to evaluate all possibilities.
Can seizure medications interfere with diabetes control?
Some seizure medications can affect blood sugar levels or interact with diabetes medications. If you are prescribed a seizure medication, tell your doctor about your diabetes and all diabetes medications you take. Your doctor may need to adjust doses or monitor your blood sugar more closely. Do not stop taking either medication without medical guidance.