Hypoglycemia Classification and Blood Sugar Thresholds
Hypoglycemia is defined as a blood glucose level less than 70 mg/dL (3.9 mmol/L), with different severity levels based on specific glucose thresholds and clinical manifestations. 1
Classification of Hypoglycemia
The American Diabetes Association classifies hypoglycemia into three distinct levels:
Level 1 Hypoglycemia
- Definition: Blood glucose <70 mg/dL (3.9 mmol/L) but ≥54 mg/dL (3.0 mmol/L)
- Significance: This is the threshold for neuroendocrine responses to falling glucose in people without diabetes
- Clinical importance: Considered clinically important regardless of symptoms, especially in patients with diabetes who may have impaired counterregulatory responses 1
Level 2 Hypoglycemia
- Definition: Blood glucose <54 mg/dL (3.0 mmol/L)
- Significance: This is the threshold at which neuroglycopenic symptoms begin to occur
- Action required: Requires immediate intervention to resolve the hypoglycemic event 1
Level 3 Hypoglycemia
- Definition: A severe event characterized by altered mental and/or physical functioning requiring assistance from another person for recovery
- Note: No specific glucose threshold is defined as it's based on clinical presentation rather than a specific glucose value 1
Clinical Implications
The 70 mg/dL threshold is recognized as clinically important because:
- It triggers neuroendocrine responses in people without diabetes
- Many people with diabetes have impaired counterregulatory responses or hypoglycemia unawareness 1
Symptoms of hypoglycemia may include shakiness, irritability, confusion, tachycardia, sweating, and hunger, but may not be present in patients with hypoglycemia unawareness 1
Level 2 hypoglycemia (<54 mg/dL) requires immediate action as neuroglycopenic symptoms typically begin at this level 1
Treatment Approach
For conscious individuals with hypoglycemia (glucose <70 mg/dL):
- Administer 15-20g of glucose or any form of carbohydrate containing glucose
- Recheck blood glucose after 15 minutes
- Repeat treatment if hypoglycemia persists 1
Important Considerations
- Patients at high risk for hypoglycemia should be monitored closely, especially those on insulin or sulfonylureas 1
- One or more episodes of level 2 or 3 hypoglycemia should prompt reevaluation of the treatment plan 1
- Continuous glucose monitoring (CGM) is beneficial and recommended for individuals at high risk for hypoglycemia 1
In summary, any blood glucose level below 70 mg/dL (3.9 mmol/L) is considered hypoglycemia, with increasing severity and risk as glucose levels fall below 54 mg/dL (3.0 mmol/L) or when assistance is required for recovery.