Symptoms of Hypoglycemia
Hypoglycemia presents with two distinct categories of symptoms: autonomic (adrenergic) symptoms occurring first as blood glucose falls below 70 mg/dL, followed by neuroglycopenic symptoms as glucose drops below 54 mg/dL. 1
Autonomic (Adrenergic) Symptoms
These symptoms result from the body's counterregulatory response and typically appear first:
- Shakiness/tremor - one of the most common early warning signs 1
- Sweating - reported in approximately 26-27% of severe hypoglycemic episodes 1, 2
- Tachycardia/palpitations - cardiovascular response to falling glucose 1, 3
- Hunger - a classic autonomic symptom 1
- Irritability - early behavioral change 1, 3
Neuroglycopenic Symptoms
These symptoms reflect direct brain glucose deprivation and indicate more severe hypoglycemia:
- Confusion/disorientation - reported in 22-29% of severe episodes and frequently seen as a consequence 1, 2
- Weakness/fatigue - the most frequently reported symptom in severe hypoglycemia (29-30% of cases) 2
- Drowsiness - indicates worsening neuroglycopenia 3, 4
- Blurred vision/visual disturbances - common early neuroglycopenic sign 3
- Difficulty speaking/speech difficulties - indicates significant brain glucose deprivation 4
- Incoordination - motor function impairment 4
- Odd behavior - behavioral changes requiring assistance 4
Severe Hypoglycemia Manifestations (Level 3)
When hypoglycemia progresses untreated, life-threatening symptoms develop:
- Loss of consciousness - occurs in approximately 25% of severe hypoglycemic events 2
- Seizures/convulsions - can occur with prolonged severe hypoglycemia 1, 3
- Coma - requires immediate emergency intervention 1
- Altered mental and/or physical status requiring assistance - the defining feature of level 3 hypoglycemia regardless of measured glucose level 1
Clinical Classification by Severity
The American Diabetes Association defines three levels of hypoglycemia with distinct symptom patterns 1:
- Level 1 (glucose 54-69 mg/dL): Primarily autonomic symptoms; patient can self-treat 1
- Level 2 (glucose <54 mg/dL): Neuroglycopenic symptoms begin; requires immediate action 1
- Level 3: Severe cognitive/physical impairment requiring assistance, irrespective of glucose level 1
Important Clinical Caveats
Many patients with diabetes develop impaired hypoglycemia awareness, meaning they lose the ability to recognize autonomic warning symptoms before neuroglycopenic symptoms appear. 1 This condition dramatically increases the risk of severe hypoglycemia and should be screened for at every clinical encounter. 1
None of these symptoms is specific to hypoglycemia alone - they must be differentiated from neurologic, psychiatric, and cardiovascular disorders. 4 Confirmation requires documented low blood glucose concurrent with symptoms.
Immediate Management
For conscious patients with glucose <70 mg/dL, administer 15-20 grams of glucose (preferred) or any carbohydrate containing glucose. 1 Repeat blood glucose measurement after 15 minutes and retreat if hypoglycemia persists. 1
For severe hypoglycemia with altered mental status or inability to take oral carbohydrates, glucagon administration is indicated. 1, 5 The dose is 1 mg for adults and children weighing >25 kg, or 0.5 mg for children <25 kg, administered subcutaneously, intramuscularly, or intravenously. 5 If no response occurs after 15 minutes, repeat the dose while awaiting emergency assistance. 5
After recovery, provide oral carbohydrates immediately - both fast-acting (regular soft drink, fruit juice) and long-acting sources (crackers with cheese or meat sandwich) to restore hepatic glycogen and prevent recurrence. 5
Precipitating Factors
Approximately 48-58% of severe hypoglycemic episodes are preceded by variations in food intake (delayed or missed meals), making many episodes potentially preventable. 2 Other common antecedents include physical exercise, alcohol consumption, and medication errors. 6