Glucose serves as the primary energy source for the brain, fueling its complex functions, including thought, memory, and learning. When glucose levels in the bloodstream fall too low, a condition known as hypoglycemia occurs. This deprivation of the brain’s main fuel can lead to a cascade of neurological symptoms, which in severe cases, may include seizures.
How Low Glucose Affects the Brain
The brain consumes approximately 20% of the body’s glucose-derived energy, requiring a continuous supply from the bloodstream. Unlike muscles and the liver, the brain cannot directly use fatty acids for fuel. When blood glucose concentrations drop below a healthy range, typically below 70 mg/dL (3.9 mmol/L), the brain’s cells, particularly neurons, begin to malfunction.
This glucose deprivation impairs the production of ATP, the energy currency of cells, and can disrupt the synthesis of neurotransmitters, which are the brain’s chemical messengers. As communication between neurons breaks down, brain function becomes increasingly compromised. If glucose levels continue to fall, the brain experiences significant functional failure, leading to cognitive impairment, aberrant behaviors, and potentially seizures or coma.
Common Causes of Hypoglycemia
Hypoglycemia frequently occurs in individuals with diabetes, particularly those using insulin or certain oral diabetes medications like sulfonylureas, due to an imbalance between medication, food intake, and physical activity. Taking too much insulin, injecting the wrong type of insulin, or miscalculating the carbohydrate content of a meal can lead to an excess of insulin relative to available glucose. Waiting too long to eat after administering mealtime insulin can also cause blood sugar to drop.
Skipping or delaying meals, or not consuming enough carbohydrates, can deplete the body’s glucose stores. Increased physical activity can heighten the body’s sensitivity to insulin and increase glucose utilization by muscles, potentially causing hypoglycemia. Alcohol consumption can also induce hypoglycemia by interfering with the liver’s ability to release stored glucose.
Certain medical conditions and tumors can also cause hypoglycemia in individuals without diabetes. Tumors of the pancreas, known as insulinomas, can produce excessive amounts of insulin. Other non-islet cell tumors can cause hypoglycemia by producing insulin-like growth factors that mimic insulin’s effects. Severe illnesses, prolonged starvation, or certain hormone deficiencies can also impair the body’s ability to maintain adequate blood glucose levels.
Recognizing Hypoglycemic Seizures
Recognizing a hypoglycemic seizure can be challenging as its symptoms can sometimes mimic other conditions. Early signs of hypoglycemia often precede a seizure and may include shakiness, sweating, dizziness, hunger, anxiety, and a rapid heartbeat. As blood glucose levels continue to fall, more pronounced neurological symptoms can emerge, such as confusion, difficulty concentrating, slurred speech, clumsiness, unusual behavior, or blurred vision.
When hypoglycemia becomes severe enough to trigger a seizure, observable characteristics may include loss of consciousness, uncontrolled shaking or convulsions, muscle rigidity, and twitching. In some instances, there may be tongue biting or loss of bladder control. After the seizure, the individual may experience fatigue, headache, and have no memory of the event.
What to Do During a Hypoglycemic Seizure
Immediate action is necessary when witnessing a suspected hypoglycemic seizure. If the person is conscious and able to swallow safely, administer a fast-acting source of glucose promptly. This can include 15-20 grams of carbohydrates from glucose tablets, half a cup of fruit juice, regular soda (not diet), or one tablespoon of honey or syrup. After 15 minutes, recheck their blood sugar if a meter is available; if it remains below 70 mg/dL, repeat the glucose administration.
If the individual is unconscious, unable to swallow, or experiencing convulsions, do not attempt to give them food or drink by mouth, as this poses a choking hazard. Instead, if a glucagon emergency kit is available and you are trained to use it, administer the glucagon injection immediately. Glucagon is a hormone that stimulates the liver to release stored glucose, rapidly raising blood sugar levels. Even after administering glucagon, or if a kit is unavailable, call emergency services (911) without delay. Once glucagon has been given, turn the person onto their side, as glucagon can sometimes cause vomiting.
Preventing Future Episodes
Preventing recurrent low glucose episodes and associated seizures involves a multi-faceted approach focused on consistent management and lifestyle adjustments. Key strategies include:
Regular blood glucose monitoring: For individuals with diabetes, this is important for timely intervention before levels drop low. This includes checking blood sugar before and after meals, exercise, and at bedtime.
Consistent meal planning: Regular meals and snacks with appropriate carbohydrate content help maintain stable blood sugar levels.
Proper medication management: Take insulin or other diabetes medications as prescribed, adjusting dosages based on food intake and activity levels.
Awareness of exercise impact: Understand how exercise affects blood sugar and adjust carbohydrate intake or medication accordingly to prevent exercise-induced hypoglycemia.
Carrying fast-acting glucose sources: Always have glucose tablets or juice available for unexpected drops in blood sugar.