Hypoglykemia

Hypoglykemia, or low blood glucose, is a medical condition defined by a plasma glucose concentration that falls below levels sufficient to meet the brain’s needs. Clinically, it is often considered present when glucose is at or below 70 mg/dL (3.9 mmol/L), especially if symptoms are developing. Symptoms can be adrenergic, such as sweating, tremor, palpitations, and anxiety, or neuroglycemic, including confusion, irritability, difficulty speaking, blurred vision, seizures, or loss of consciousness. The onset can be rapid and the severity can vary with age and circumstance.

Causes and risk factors vary. In people with diabetes, the most common cause is excess insulin or other glucose-lowering medications, combined with missed meals, increased physical activity, or alcohol use. Non-diabetic causes include prolonged fasting, heavy alcohol consumption, critical illness, adrenal or pituitary insufficiency, liver or kidney disease, and certain medications. Children, older adults, and those with irregular eating patterns may be particularly susceptible.

Diagnosis relies on measuring blood glucose at the time of symptoms. In clinical settings, venous plasma glucose is used, and a reading below 70 mg/dL alongside symptoms supports the diagnosis. It is important to rule out pseudohypoglycemia and to verify with a repeat test if needed.

Management depends on the patient’s level of consciousness. Conscious individuals who can swallow should ingest 15-20 grams of fast-acting carbohydrates (such as glucose tablets or juice), then recheck after 15 minutes and repeat if necessary. Once stable, a small snack or meal helps maintain levels. If the person is unconscious or cannot swallow, seek emergency help and administer glucagon as directed; in healthcare settings, intravenous dextrose may be given. Prevention involves medication adjustments, carrying fast-acting carbohydrates, monitoring glucose regularly, and having a written plan for exercise, illness, or missed meals.