The brain is the body’s most energy-demanding organ, relying almost entirely on a steady supply of glucose to fuel its operations. This dependence means that any significant drop in blood glucose levels, known as hypoglycemia, quickly impacts neurological function. When the brain is deprived of its primary fuel source, the resulting impairment can manifest as an acute state of severe mental confusion and disorientation called delirium.
Confirming the Link Between Hypoglycemia and Delirium
Low blood sugar is a well-established cause of reversible delirium or acute altered mental status. This profound confusion is the direct result of the brain being starved of glucose, a state termed neuroglycopenia. While blood glucose levels below 70 milligrams per deciliter (mg/dL) are classified as hypoglycemia, delirium-inducing symptoms often appear when levels drop further, typically below 54 mg/dL.
The brain possesses no significant internal stores of glucose, unlike muscle or liver tissue, making it uniquely vulnerable to blood sugar fluctuations. When this fuel supply dwindles, the central nervous system begins to shut down, leading to functional brain failure. The resulting confusion is a medical emergency because, if left untreated, severe hypoglycemia can rapidly progress to seizures, coma, or permanent neurological damage.
How Glucose Deprivation Disrupts Brain Function
Glucose is not merely a source of energy for the brain; it is also a necessary precursor for synthesizing neurotransmitters, the chemical messengers that facilitate communication between neurons. When blood glucose concentration plummets, the production of adenosine triphosphate (ATP), the cell’s energy currency, is curtailed. This energy failure compromises the function of sodium-potassium pumps on neuronal membranes, which maintain the electrical potential necessary for transmitting signals.
The disruption extends to the balance of excitatory and inhibitory neurotransmitters, which are essential for normal cognitive processing. Glucose is needed to maintain the homeostasis of amino acid neurotransmitters like glutamate and gamma-aminobutyric acid (GABA). When glucose is scarce, this chemical communication breaks down, leading to disorganized neuronal activity throughout the cerebrum. This metabolic stress on the neurons is the root cause of the cognitive impairment and behavioral changes seen in hypoglycemic delirium.
Identifying Symptoms of Delirium and Acute Confusion
Delirium caused by hypoglycemia represents an escalation of symptoms, distinct from initial warning signs like sweating, shakiness, or a fast heartbeat. These neuroglycopenic symptoms occur when the brain is impaired by the lack of fuel. A person in this state will exhibit a rapid, acute change in their usual mental status.
Symptoms commonly include disorientation, inability to follow commands, and difficulty with concentration or attention. Behavioral changes can range from lethargy and unresponsiveness (hypoactive delirium) to agitation, belligerence, or aggression (hyperactive delirium). Slurred speech, loss of coordination, and inability to perform routine tasks are common indicators of this neurological crisis. These presentations often mimic other conditions, such as intoxication or a stroke, requiring immediate blood glucose testing to determine the cause.
Immediate Actions and Emergency Treatment
Treating hypoglycemia that has progressed to delirium requires immediate action to restore the brain’s glucose supply. For a person who is conscious and able to swallow, the protocol involves the “Rule of 15.” This means consuming 15 to 20 grams of fast-acting carbohydrates, such as glucose tablets, fruit juice, or regular soda, and rechecking the blood sugar level after 15 minutes. This process is repeated until the blood glucose is above 70 mg/dL.
If the person is unconscious, severely confused, or unable to swallow, they should not be given food or liquid by mouth due to the risk of choking or aspiration. Immediate medical assistance must be called. If available and the caregiver is trained, an emergency glucagon injection or nasal spray should be administered. Glucagon is a hormone that prompts the liver to release stored glucose, providing a surge of sugar to the brain. Once the glucose level has stabilized, a small snack or meal containing complex carbohydrates should be consumed to prevent a subsequent blood sugar drop.