Individuals with diabetes can experience seizures due to extreme fluctuations in blood sugar levels. These events, often called metabolic seizures, are a medical emergency resulting from the brain’s dependence on a steady supply of glucose for proper function. The primary cause is severe hypoglycemia (dangerously low blood sugar), which starves the brain of energy. Less commonly, extreme hyperglycemia (very high blood sugar) can also trigger seizure activity through complex metabolic imbalances. Understanding the specific causes and knowing the correct emergency response is important for anyone living with or caring for someone with diabetes.
Hypoglycemia The Immediate Cause
The most frequent metabolic cause of seizures in people with diabetes is severe hypoglycemia, defined by a blood glucose reading typically falling below 54 mg/dL. The brain is unique because it relies almost entirely on glucose for fuel, unlike other organs. When blood sugar drops to a critically low level, the brain cells, or neurons, become starved of energy, a condition called neuroglycopenia.
This energy deprivation disrupts the normal electrical signaling pathways within the brain, leading to neurological dysfunction that can manifest as confusion, altered consciousness, and eventually, a seizure. Seizure activity in this context is essentially the brain’s electrical system short-circuiting due to lack of fuel. Common triggers that can cause this severe drop include taking too much insulin or other glucose-lowering medication, missing a meal, or engaging in unusually intense or prolonged physical activity without adjusting carbohydrate intake.
The onset of a hypoglycemic seizure often follows earlier, milder symptoms like shakiness, sweating, and rapid heartbeat, which are the body’s natural warnings to raise blood sugar. However, in some individuals, particularly those who have had diabetes for a long time, these warning signs can diminish, a dangerous state known as hypoglycemia unawareness. Without these preliminary signals, the blood sugar can drop directly to the seizure-inducing threshold with little warning, leading to convulsions and loss of consciousness.
Hyperglycemic States and Seizure Risk
While less common than those caused by low blood sugar, seizures can also occur when blood sugar levels are extremely high (hyperglycemia). This risk is primarily associated with two life-threatening complications of diabetes: Diabetic Ketoacidosis (DKA) and Hyperosmolar Hyperglycemic State (HHS).
Hyperosmolar Hyperglycemic State (HHS)
In HHS, blood glucose levels can be extremely elevated, often reaching several hundred milligrams per deciliter, leading to severe dehydration and dangerously concentrated blood plasma (hyperosmolarity). This profound shift causes fluid to be pulled out of the brain cells, which can trigger seizure activity and other neurological symptoms like confusion and coma. Seizures in HHS are frequently focal, meaning they begin in a specific area of the brain.
Diabetic Ketoacidosis (DKA)
In DKA, the body produces high levels of acidic ketones as it burns fat for fuel due to a lack of insulin, creating metabolic acidosis. Although seizures are rare in DKA, the underlying severe dehydration and electrolyte imbalances, such as low sodium levels, contribute to a lowered seizure threshold. The acidity in the blood and the resulting osmotic changes can impair brain function.
Emergency Response and First Aid
A metabolic seizure is a medical emergency that requires immediate and specific action from a bystander. The first and most important step is to ensure the person’s safety by gently moving away any nearby objects that could cause injury, such as furniture. Do not attempt to restrain the person or place anything in their mouth, as this can cause harm. If the seizure lasts for more than five minutes, or if the person does not wake up or regain consciousness shortly after the seizure stops, emergency medical services, such as 911, must be called immediately. If a person is found unconscious and is known to have diabetes, severe hypoglycemia should be assumed as the most likely cause.
Administering Glucose
For an unconscious person, the bystander should administer emergency glucagon, if a kit is readily available and they are trained to use it. Glucagon is a hormone that causes the liver to release stored glucose into the bloodstream, rapidly raising blood sugar. If the person is conscious but disoriented or unable to swallow, a fast-acting source of sugar, such as a glucose gel, can be rubbed into the cheek pouch. Never try to give an unconscious person food or liquid by mouth, as there is a serious risk of choking. Once the person is awake and able to swallow safely, they should consume a source of fast-acting carbohydrate, like juice or glucose tablets, followed by a snack containing protein and complex carbohydrates to stabilize blood sugar levels.
Reducing the Risk of Metabolic Seizures
Proactive management of diabetes is the most effective strategy for preventing metabolic seizures. Consistent monitoring of blood glucose levels is essential, which includes checking with a traditional meter or using a Continuous Glucose Monitor (CGM) for real-time data. CGM systems can provide predictive alerts when blood sugar is trending dangerously low or high, allowing for intervention before an emergency develops. Individuals must be able to recognize the early warning signs of both hypo- and hyperglycemia to intervene promptly.
- Symptoms of low blood sugar include mild confusion, slurred speech, or unusual irritability.
- Symptoms of high blood sugar include extreme thirst, frequent urination, and nausea.
Proper medication adherence, including taking the correct dose of insulin or oral medication at the right time, is a simple yet effective preventative measure. Carrying emergency glucose supplies, such as glucose tablets or gel, at all times is necessary for quickly treating low blood sugar episodes. Individuals who use insulin should have a prescription for an emergency glucagon kit, and family members or close contacts should be trained on how to administer it. Regular, open communication with a healthcare provider is essential to adjust medication dosages, review monitoring data, and create a personalized plan for avoiding these dangerous blood sugar extremes.