• Reactive hypoglycemia, also called Postprandial hypoglycemia, occurs within 4 hours after meals.
• Fasting hypoglycemia, also called postabsorptive hypoglycemia, is often related to an underlying disease.
This classification was based on the assumption that fasting hypoglycemia is caused by organic pathologies presenting mostly with neuroglycopenic symptoms and reactive hypoglycemia arises from functional disorder presenting mostly with autonomic features.
Fasting hypoglycemia is defined as the inability to maintain glucose homeostasis in the postabsorptive, or fasting, state: An example is an insulinoma, an insulin secreting tumor of the islets of Langerhans.
Postabsorptive hypoglycemia occurs when both glucagon and epinephrine are deficient, but not when either glucagon or epinephrine alone is deficient, and insulin is present.
Fasting hypoglycemia occurring several (>5 h) hours after food, e.g., on waking or at night, or precipitated by prolonged fasting or exercise in the postabsorptive period.
Symptoms of both reactive and fasting hypoglycemia are similar to diabetes-related hypoglycemia. Symptoms may include hunger, sweating, shakiness, dizziness, light-headedness, sleepiness, confusion, difficulty speaking, anxiety, and weakness.
Causes of fasting hypoglycemia include certain medications, alcoholic beverages, critical illnesses, hormonal deficiencies, some kinds of tumors, and certain conditions occurring in infancy and childhood.
Postabsorptive/Fasting hypoglycemia
