Insulin is a hormone produced naturally by the pancreas that manages glucose, the body’s primary fuel source circulating in the bloodstream. Its function is to act as a “key,” allowing glucose to move from the blood into the body’s cells, where it is used for energy or stored for later use. Administering this hormone as medication helps to lower elevated blood sugar levels for many people with diabetes. When a dose significantly exceeds the body’s requirement, it results in the excessive removal of glucose from the blood. This steep and rapid decline in circulating sugar levels creates a dangerous state of energy deprivation.
The Mechanism of Low Blood Sugar
Hypoglycemia is the physiological state resulting from excess insulin, clinically defined for many people with diabetes as a blood glucose level falling below 70 milligrams per deciliter (mg/dL). Surplus insulin promotes the uncontrolled uptake of glucose into muscle, fat, and liver cells. This action strips the blood of its sugar content, interrupting the necessary fuel supply to the central nervous system. The brain relies almost exclusively on a continuous supply of glucose; when this supply drops too low, the condition is termed neuroglycopenia. The body attempts to counteract this sudden drop by releasing counter-regulatory hormones like glucagon and epinephrine, which signal the liver to release stored glucose. However, an overwhelming insulin dose can quickly overpower these natural defenses.
Identifying Warning Signs
The initial, milder symptoms of low blood sugar result from the body’s counter-regulatory hormones, specifically adrenaline, surging through the system. These autonomic nervous system responses manifest as shakiness, cold sweats, a faster heart rate, and anxiety or nervousness. Hunger is also a common early symptom, signaling the brain’s desperate need for fuel.
If the blood glucose level continues to fall unchecked, the symptoms transition into more severe manifestations that reflect the brain’s deprivation of energy. Neuroglycopenia causes cognitive and neurological impairments, often starting with confusion, difficulty concentrating, or uncharacteristic irritability. Speech may become slurred, and coordination can be impaired, making simple tasks difficult or impossible.
When blood sugar drops significantly below 54 mg/dL, brain function is severely impaired. This severe phase can include the inability to swallow, the onset of seizures, and ultimately, a loss of consciousness or coma. Recognizing these symptoms quickly is paramount, as the progression from mild discomfort to a medical emergency can happen rapidly.
Essential Steps for Immediate Treatment
The immediate treatment protocol for an insulin overdose depends on whether the person is conscious and able to swallow. For mild to moderate symptoms where the person is fully alert, the “Rule of 15” protocol should be followed. This involves consuming 15 grams of a fast-acting carbohydrate to raise blood glucose levels quickly. Suitable sources include four ounces of fruit juice, half a can of regular soda, or three to four glucose tablets.
After consuming the carbohydrate, wait 15 minutes before rechecking the blood sugar level. If the blood sugar remains below 70 mg/dL, the 15-gram carbohydrate dose should be repeated until the level is above this threshold. Once the blood sugar has stabilized, eat a small snack containing protein and a longer-acting carbohydrate, such as crackers with cheese, to prevent the level from dropping again.
In the event of severe hypoglycemia where the person is unconscious, having a seizure, or unable to safely swallow, no food or liquid should be given by mouth. This situation requires the administration of emergency glucagon, a prescription hormone that triggers the liver to release its stored glucose rapidly into the bloodstream. If glucagon is not available or if the person remains unconscious 15 minutes after the injection, emergency medical services must be called.
Preventing Accidental Insulin Overdose
To minimize the risk of accidental overdose, always double-check the intended dosage against the final setting on an insulin pen or syringe before injection. A common mistake involves confusing different types of insulin, such as accidentally taking a rapid-acting dose instead of a basal (long-acting) dose, which can lead to a sudden and profound drop in blood sugar. To avoid this, individuals can label or color-code their different insulin types and keep them physically separated.
The timing of the dose relative to eating is a significant factor in preventing an overdose. Rapid-acting insulin should be followed by a meal shortly after injection; skipping or delaying a meal can lead to an unexpected low blood sugar event. Consulting regularly with a healthcare provider or pharmacist is beneficial to ensure the prescribed insulin regimen is optimized for current lifestyle factors and to review proper injection techniques.