What are the diagnostic criteria for reactive hypoglycemia (low blood sugar)?

From the Guidelines

Reactive hypoglycemia is diagnosed through a combination of symptom evaluation, blood glucose monitoring, and specialized testing, with a blood glucose level below 70 mg/dL being the primary diagnostic criterion, as outlined in the standards of medical care in diabetes-2019 1. The diagnostic approach typically involves assessing symptoms such as shakiness, sweating, dizziness, hunger, and confusion that occur within 2-4 hours after eating.

• Measuring blood glucose levels when symptoms occur is the most direct diagnostic approach, with a value below 70 mg/dL confirming hypoglycemia, as this threshold is recognized for neuroendocrine responses to falling glucose in people without diabetes 1.
• A mixed meal tolerance test may be performed, where the patient consumes a standard meal and has blood glucose measured at intervals over several hours.
• Home blood glucose monitoring with a standard glucometer can also be used to document episodes.
• Sometimes, a 5-hour oral glucose tolerance test is used, though it's less preferred as it doesn't replicate normal eating. It's crucial to rule out other causes of hypoglycemia, such as medications (particularly insulin or sulfonylureas), alcohol consumption, or underlying conditions like insulinoma, as these can have significant implications for morbidity, mortality, and quality of life. Diagnosis is confirmed when documented low blood glucose coincides with typical symptoms that resolve when glucose levels are restored, allowing for appropriate management through dietary modifications and meal planning, which can significantly improve patient outcomes, especially in preventing level 3 hypoglycemia, a severe event characterized by altered mental and/or physical functioning that requires assistance from another person for recovery 1.

From the Research

Diagnostic Criteria for Reactive Hypoglycemia

The diagnostic criteria for reactive hypoglycemia include:

• Plasma glucose concentration below 3 mmol/l or 55 mg/dl at the time of malaise 2
• Symptoms such as adrenergic symptoms and cognitive disturbances 2
• Measurement of blood glucose during a postprandial symptomatic episode in the home setting 3
• Documentation of hypoglycemia in the home setting, rather than just relying on an oral glucose tolerance test (OGTT) 3, 4

Forms of Reactive Hypoglycemia

Reactive hypoglycemia can occur in different forms, including:

• Idiopathic reactive hypoglycemia (at 180 min) 5
• Alimentary reactive hypoglycemia (within 120 min) 5, 3
• Late reactive hypoglycemia (at 240-300 min) 5
• Reactive hypoglycemia due to late dumping syndrome 6

Diagnostic Tests

Diagnostic tests for reactive hypoglycemia include:

• Oral glucose tolerance test (OGTT) 5, 3, 4
• Ambulatory glycemic control 4
• Hyperglucidic breakfast test 4
• Measurement of plasma glucose concentration during a postprandial symptomatic episode 2, 3

Treatment

Treatment for reactive hypoglycemia includes:

• Dietary restriction of refined carbohydrates 3, 4
• Frequent small split meals and limitation of carbohydrates with high glycaemic index 2
• Acarbose, a specific inhibitor of gut alpha-glucosidase enzymes 2, 6
• Alpha-glucosidase inhibitors and some other drugs may be helpful 4