Signs of Hypoglycemia
Hypoglycemia presents with two distinct categories of symptoms: adrenergic (autonomic) symptoms that occur first as warning signs, followed by neuroglycopenic symptoms when blood glucose drops further. 1
Adrenergic (Autonomic) Symptoms - Early Warning Signs
These symptoms result from the sympathetic nervous system's counterregulatory response and typically appear first when blood glucose falls below 70 mg/dL:
Neuroglycopenic Symptoms - More Severe Hypoglycemia
These symptoms occur when blood glucose drops below 54 mg/dL and reflect inadequate glucose delivery to the brain:
- Confusion/disorientation 1, 2, 5
- Irritability 1, 5
- Drowsiness/somnolence 1, 6
- Lightheadedness/dizziness 1, 4
- Blurred vision 4
- Weakness/fatigue 2
- Headache 4
Severe Hypoglycemia (Level 3) - Medical Emergency
When hypoglycemia progresses untreated, it leads to severe neuroglycopenia requiring immediate intervention:
- Altered mental status 1, 3
- Loss of consciousness 1, 2, 4
- Stupor or coma 1, 5, 6
- Seizures/convulsions 1, 4
- Inability to self-treat (requires assistance from another person) 1
Critical Clinical Pearls
The progression of symptoms is predictable but timing varies by individual. 1 Most people experience adrenergic symptoms first, providing an opportunity for self-treatment before neuroglycopenic symptoms develop. 1
Impaired hypoglycemia awareness is a dangerous condition where patients lose the early warning adrenergic symptoms and progress directly to neuroglycopenic symptoms without warning. 1 This should be screened for at least annually in all at-risk patients. 1
Symptoms alone are insufficient for diagnosis - a measured glucose <70 mg/dL (<3.9 mmol/L) is required, as symptoms can be nonspecific and variable between individuals. 1, 7