Insulin is a hormone that plays a fundamental role in regulating the body’s metabolism, primarily by managing blood sugar, or glucose, levels. Its function is to signal cells throughout the body to absorb glucose from the bloodstream for energy or storage. An insulin “overdose” refers to a situation where an excessive amount of the hormone is present, rapidly clearing too much glucose from the blood. This leads directly to severe hypoglycemia, which is dangerously low blood sugar. This condition is a time-sensitive medical emergency that can rapidly endanger the central nervous system.
The Physiological Mechanism of Overdose
When a person receives a dose of insulin exceeding their physiological need, the hormone works aggressively to remove glucose from circulation. Insulin binds to receptors on muscle, fat, and liver cells, signaling them to ramp up the uptake of glucose. The surplus insulin pulls sugar out of the bloodstream and into storage sites at an uncontrolled rate. This rapid clearance quickly starves the body’s primary energy consumer, the brain. The brain is dependent on a continuous supply of glucose for fuel, as it cannot store large amounts of it. When blood glucose drops below a critical threshold (typically below 70 milligrams per deciliter (mg/dL)), the brain suffers from a lack of necessary energy. This neurological deficit, known as neuroglycopenia, is the direct cause of the symptoms and dangers associated with an insulin overdose.
Recognizing the Early Warning Signs
The initial symptoms of an insulin overdose stem from the body’s counter-regulatory response, which is the release of hormones like adrenaline to raise blood sugar. Physical signs include sudden sweating, cold clamminess, and tremors or shakiness. The person might also notice a rapid or pounding heartbeat, which is the body’s attempt to circulate blood faster. Mental and emotional changes are common early indicators due to the brain’s reduced glucose supply. These neuroglycopenic symptoms can present as nervousness, anxiety, irritability, or disorientation. A strong, sudden feeling of hunger, known as polyphagia, is another classic warning sign. Recognizing these symptoms is a time-sensitive step, as the individual may still be conscious and able to self-treat with fast-acting carbohydrates.
The Progression to a Life-Threatening Emergency
If the early warning signs are missed or treatment is delayed, the lack of glucose causes the symptoms to progress into a severe, life-threatening emergency. As the brain’s energy supply dwindles, the effects on the central nervous system become profound. Mild confusion gives way to significant cognitive impairment, including slurred speech and profound lethargy. This severe stage of neuroglycopenia can lead to loss of muscle control and uncoordinated movements. Without intervention, prolonged glucose deprivation can trigger seizures. The ultimate consequence is the progression to loss of consciousness, stupor, or a hypoglycemic coma. If the brain is deprived of glucose for an extended period, the outcome can include permanent neurological damage or death.
Emergency Protocol and Immediate Action
Immediate action is paramount when an insulin overdose is suspected, and the steps depend on the person’s level of consciousness.
Conscious Individuals
For an individual who is still awake and able to swallow safely, treatment involves consuming 15 to 20 grams of fast-acting glucose immediately. This includes sources such as four ounces of fruit juice, a regular soda, or three to four glucose tablets. This concentrated sugar source is absorbed quickly to counteract the effects of the excess insulin.
Unconscious Individuals
If the person becomes disoriented, has a seizure, or loses consciousness, oral treatment is unsafe due to the risk of choking. Emergency services (911) must be contacted right away. If available and the caregiver is trained, an injection of glucagon should be administered. Glucagon is a hormone that acts as a direct antidote to insulin, signaling the liver to release its stored glucose.
Even after glucagon is administered or consciousness returns, the individual requires medical attention, and monitoring must continue for several hours. The duration of the overdose effect depends on the type of insulin taken, as long-acting insulins can cause recurrent hypoglycemia for a day or more. The medical team will stabilize the blood sugar, often using intravenous dextrose, and ensure the person is safe from further drops in glucose levels.