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, with severe cases progressing to altered mental status, loss of consciousness, seizures, or coma requiring immediate treatment with glucose or glucagon. 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
- Hunger - a classic autonomic symptom 1
- Irritability - early behavioral change 1
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 1, 3
- Blurred vision - common early neuroglycopenic sign 4
- Difficulty with speech - indicates significant brain glucose deprivation 3
- Incoordination - motor function impairment 3
- Odd behavior - behavioral changes requiring recognition by others 3
Severe Hypoglycemia Manifestations
Level 3 hypoglycemia is defined as altered mental and/or physical status requiring assistance from another person for recovery, regardless of measured glucose level: 1
- Loss of consciousness - occurs in approximately 25% of severe hypoglycemic events 2
- Seizures/convulsions - can occur if glucose remains critically low 1, 4
- Coma - represents life-threatening neuroglycopenia 1, 4
- Death - rare but possible if blood glucose remains low for extended periods (12+ hours) 4
Clinical Classification by Glucose Levels
The American Diabetes Association defines three levels of hypoglycemia with corresponding symptom severity: 1
- Level 1: Glucose 54-69 mg/dL (3.0-3.9 mmol/L) - autonomic symptoms predominate, patient can self-treat 1
- Level 2: Glucose <54 mg/dL (<3.0 mmol/L) - threshold where neuroglycopenic symptoms begin, requires immediate action 1
- Level 3: Severe event with altered mental/physical status requiring assistance, irrespective of glucose level 1
Important Clinical Caveats
Many patients with diabetes develop impaired hypoglycemia awareness, meaning they may not experience typical autonomic warning symptoms before neuroglycopenic symptoms appear, making them vulnerable to sudden severe hypoglycemia. 1
- Symptoms are not specific to hypoglycemia and must be differentiated from neurologic, psychiatric, and cardiovascular disorders 3
- Recurrent hypoglycemia can blunt counterregulatory responses and reduce symptom awareness 1
- Nocturnal hypoglycemia may occur without awakening the patient, particularly in insulin-treated individuals 5
- Cognitive impairment or dementia increases risk for both hypoglycemia and reduced symptom recognition 1
Immediate Management
For conscious patients with glucose <70 mg/dL, administer 15-20 grams of glucose (preferred) or any carbohydrate containing glucose, then recheck glucose in 15 minutes and repeat treatment if hypoglycemia persists. 1
For severe hypoglycemia with altered mental status or inability to take oral carbohydrates, glucagon must be administered immediately by subcutaneous, intramuscular, or intravenous injection. 1, 6
- Adults and children >25 kg or ≥6 years: 1 mg glucagon 6
- Children <25 kg or <6 years: 0.5 mg glucagon 6
- If no response after 15 minutes, repeat the dose while awaiting emergency medical services 6
- Once the patient can swallow, provide oral carbohydrates to restore liver glycogen and prevent recurrence 6