OVERVIEW

What is reactive hypoglycemia?

Reactive hypoglycemia, also known as "idiopathic postprandial hypoglycemia," "functional postprandial hypoglycemia," or "stimulative hypoglycemia."

It is characterized by hypoglycemic episodes related to food intake, particularly after consuming large amounts of carbohydrates. Hypoglycemia typically occurs 2–4 hours after a meal and does not occur during fasting.

Is reactive hypoglycemia common?

Reactive hypoglycemia is uncommon in daily life, but there is currently a lack of specific data on its incidence rate.

SYMPTOMS

What are the common manifestations of reactive hypoglycemia?

Reactive hypoglycemia is mainly seen in emotionally unstable individuals, often triggered by psychological stress or anxiety. Hypoglycemic episodes typically occur after breakfast but not during fasting, and are less common after lunch or dinner. Each episode lasts 15–20 minutes and resolves spontaneously.

Symptoms of hypoglycemia include palpitations, sweating, pallor, hunger, weakness, hand tremors, and slightly elevated blood pressure. Generally, there is no coma or convulsions, though fainting may occasionally occur.

Fasting blood glucose levels are normal, while postprandial hypoglycemic episodes show blood glucose levels below 2.8 mmol/L, occasionally below 2.5 mmol/L. However, plasma insulin and the insulin release index (plasma insulin/blood glucose ratio) remain normal. Patients can tolerate a 72-hour fast and have no family history of diabetes.

What severe consequences can reactive hypoglycemia cause?

Reactive hypoglycemia is largely influenced by social environment, occupation, and psychological factors, so it often resolves spontaneously. It does not impair daily life or work capacity and causes no substantial physical harm.

CAUSES

What causes reactive hypoglycemia?

Some cases of reactive hypoglycemia may be related to dysfunction in neuroendocrine regulation, increased insulin sensitivity, downregulation of insulin receptors, and decreased receptor sensitivity.

Some cases of reactive hypoglycemia may be associated with increased vagal nerve tension, which accelerates gastric emptying and slightly increases insulin secretion.

Who is more likely to experience reactive hypoglycemia?

Reactive hypoglycemia is more common in individuals prone to emotional tension or agitation, with a higher prevalence in women than in men. It frequently occurs in people aged 30–40 and is rare in those under 20 or over 50.

Is reactive hypoglycemia hereditary?

There is no clear evidence linking reactive hypoglycemia to heredity.

DIAGNOSIS

How is reactive hypoglycemia diagnosed?

When diagnosing reactive hypoglycemia, doctors primarily rely on clinical manifestations and laboratory tests while ruling out conditions such as type 2 diabetes, alimentary hypoglycemia (including dumping syndrome), parenteral nutrition support, and congenital defects in carbohydrate metabolism enzymes (e.g., hereditary fructose intolerance, galactosemia) before making a definitive diagnosis.

What tests are needed when reactive hypoglycemia is suspected?

Common tests include blood glucose measurement, an extended oral glucose tolerance test (OGTT, which may be prolonged up to 5 hours after glucose ingestion if necessary), and plasma insulin level assessment.

• Blood glucose test: Confirms the presence of postprandial hypoglycemia.

• Extended oral glucose tolerance test: Patients with reactive hypoglycemia exhibit a blood glucose drop 2–4 hours after glucose ingestion, followed by a gradual return to baseline levels. This test helps differentiate reactive hypoglycemia from other causes of postprandial hypoglycemia.

• Plasma insulin measurement: Insulin levels in reactive hypoglycemia patients show no significant increase, and the insulin-to-glucose ratio remains normal. This test aids in distinguishing reactive hypoglycemia from other postprandial hypoglycemia etiologies.

Which conditions are easily confused with reactive hypoglycemia?

Since multiple factors can cause postprandial hypoglycemia, despite reactive hypoglycemia being the most common type (accounting for ~70% of cases), it must be differentiated from other causes to avoid misdiagnosis.

• Reactive hypoglycemia: Key features include a typical anxious personality and hypoglycemic episodes. The extended OGTT shows normal blood glucose in the first 1–2 hours, followed by a drop below 2.8 mmol/L at 2–4 hours with characteristic symptoms, after which levels normalize. Symptoms resolve with a low-carbohydrate, high-protein diet.

• Alimentary hypoglycemia (including dumping syndrome): Often seen in patients post-gastrectomy, vagotomy, pyloroplasty, or gastrojejunostomy. Dumping syndrome typically occurs 15–20 minutes after meals, presenting with epigastric discomfort, bloating, nausea, weakness, dizziness, sweating, and hypotension. The extended OGTT shows a peak blood glucose ≥11.1 mmol/L in the first hour, followed by a sharp decline to hypoglycemic levels at 2–4 hours.

• Early-stage type 2 diabetes and impaired glucose tolerance: Postprandial hypoglycemia in these cases may occur with normal fasting glucose, but the OGTT curve shows a diabetic pattern (e.g., 1-hour glucose >10 mmol/L, 2-hour glucose >7.8 mmol/L, and 3–4-hour glucose dropping below 2.5 mmol/L) with hypoglycemic symptoms. Insulin release tests reveal delayed secretion, with a peak at 2–3 hours after glucose elevation, predisposing to hypoglycemia.

TREATMENT

Which department should I visit for reactive hypoglycemia?

Endocrinology, psychology, or psychiatry.

Can reactive hypoglycemia resolve on its own?

Reactive hypoglycemia has obvious self-limiting characteristics and often resolves spontaneously, with a good prognosis.

How is reactive hypoglycemia treated?

Treatment for reactive hypoglycemia includes psychotherapy, dietary habit adjustments, and medication.

• Psychotherapy: Provide reassurance and explanations about the nature of the condition, encourage physical exercise, and, if necessary, use small doses of anti-anxiety medications (e.g., diazepam) to stabilize mood.

• Dietary habit adjustments: Modify the diet to reduce carbohydrate intake, especially simple sugars (e.g., glucose, fructose), and moderately increase protein, fat, and fiber content. Eat smaller, more frequent meals, avoid overeating or fasting, and slow down eating speed.

• Medication: Anticholinergic drugs (e.g., propantheline) can delay food absorption and reduce insulin secretion, preventing hypoglycemic episodes. Calcium channel blockers (e.g., diltiazem or nifedipine) can inhibit insulin secretion, prevent hypoglycemia, and alleviate symptoms. Alpha-glucosidase inhibitors (e.g., acarbose) slow the digestion and absorption of starchy foods, reducing postprandial blood sugar spikes and allowing a gradual rise in blood sugar, which in turn reduces insulin secretion and prevents reactive hypoglycemia.

Does reactive hypoglycemia require hospitalization?

Hospitalization is recommended for the first occurrence, primarily for comprehensive diagnostic tests.

Can reactive hypoglycemia be cured?

In most cases, yes.

Reactive hypoglycemia is largely influenced by social, occupational, and psychological factors and is associated with mental health conditions. In most cases, it resolves spontaneously, leading to recovery.

DIET & LIFESTYLE

What should patients with reactive hypoglycemia pay attention to in their diet?

In terms of diet, focus on adjusting dietary structure by consuming foods that digest slowly—low in sugar, high in protein, high in fat, and high in fiber. Eat smaller, more frequent meals, choose drier foods, and slow down eating speed.

PREVENTION

Can reactive hypoglycemia be prevented?

Maintaining a cheerful mood, engaging in appropriate exercise, adjusting dietary structure, slowing down eating speed, or consuming high-fiber foods can have certain preventive effects.