Insulin is a hormone produced by specialized beta cells in the pancreas. Its primary function is to regulate the amount of glucose circulating in the bloodstream. After consuming food, glucose enters the blood, signaling the pancreas to release insulin. This hormone acts like a key, unlocking the body’s cells (particularly in the muscles, liver, and fat tissue) to allow glucose to move inside where it is used for energy or stored for future needs.
Mechanisms Behind Excess Insulin
The body can end up with higher than normal levels of insulin through different pathways. The most common acute cause is an error in managing diabetes, such as taking too much insulin medication or certain diabetes pills, or failing to eat a meal after a correct dose has been administered. This leads to a sudden flood of active insulin that rapidly clears glucose from the blood.
A second, less common cause involves the body’s own regulatory system, known as endogenous hyperinsulinemia. This can be caused by conditions like an insulinoma, a rare tumor in the pancreas that autonomously produces and secretes excessive amounts of insulin. Chronic, sustained high insulin levels often develop as a compensatory mechanism in response to insulin resistance. The body’s cells become less responsive to insulin’s signal, forcing the pancreas to overwork and secrete the hormone just to maintain normal blood sugar levels.
The Acute Crisis: Hypoglycemic Symptoms
When excess insulin causes blood glucose to drop too low (hypoglycemia), the body initiates a stress response to protect the brain, which relies almost exclusively on glucose for fuel. The initial warning signs are known as adrenergic symptoms, occurring as the body releases stress hormones like adrenaline. These symptoms include inner shakiness, a rapid heartbeat, anxiety, and excessive sweating.
As blood sugar continues to fall, typically below 55 mg/dL, the brain suffers from glucose deprivation, leading to neuroglycopenic symptoms. Cognitive and physical functions become impaired, manifesting as difficulty concentrating, confusion, slurred speech, or blurred vision. The person may also appear clumsy, irritable, or experience sudden mood changes.
The most severe stage occurs when the individual is unable to self-treat due to profound mental changes. The lack of glucose can lead to seizures, loss of consciousness, or a hypoglycemic coma. Prolonged, untreated severe hypoglycemia can result in permanent neurological damage because the brain is starved of its necessary fuel supply.
Immediate Steps for Low Blood Sugar
Treating acute low blood sugar requires immediate action to raise glucose levels back into a safe range. For mild to moderate hypoglycemia, where the person is conscious and able to swallow, the “Rule of 15” is the standard protocol. This involves consuming 15 grams of a fast-acting carbohydrate, such as four ounces of juice or regular soda, or a few glucose tablets.
After consuming the carbohydrates, the individual should wait 15 minutes and recheck their blood sugar level. If the level is still below 70 mg/dL, the 15-gram carbohydrate dose is repeated until the blood sugar is within the target range. Once normalized, it is important to eat a small snack containing protein and longer-acting carbohydrates to prevent another drop.
If a person becomes unresponsive, severely confused, or is having a seizure, they cannot safely swallow and require emergency treatment. Injectable or nasal glucagon, which causes the liver to release stored glucose, must be administered if available. Emergency medical services must be contacted immediately, as severe hypoglycemia is a life-threatening event requiring professional assistance.
Sustained Effects of Hyperinsulinemia
Chronically high insulin levels (hyperinsulinemia) extend beyond acute blood sugar drops and are linked to long-term metabolic health issues. Insulin is a powerful growth and storage hormone, and its constant presence promotes the storage of energy, particularly as fat tissue. This drives weight gain, especially around the abdomen, creating a continuous feedback loop that worsens the underlying problems.
The chronic overproduction of insulin often accelerates the development of insulin resistance, forcing the cycle of higher insulin secretion to continue. Persistently elevated insulin signaling is also implicated in cardiovascular risks. Hyperinsulinemia can contribute to high blood pressure, abnormal blood lipid levels (such as elevated triglycerides), and may promote the hardening of arteries.