Definition of Hypoglycemia
Hypoglycemia is classified into three distinct levels: Level 1 (glucose <70 mg/dL but ≥54 mg/dL), Level 2 (glucose <54 mg/dL), and Level 3 (a severe event characterized by altered mental and/or physical status requiring assistance for treatment, irrespective of glucose level). 1
Classification of Hypoglycemia
| Level | Definition |
|---|---|
| Level 1 | Glucose <70 mg/dL (<3.9 mmol/L) and ≥54 mg/dL (≥3.0 mmol/L) |
| Level 2 | Glucose <54 mg/dL (<3.0 mmol/L) |
| Level 3 | A severe event characterized by altered mental and/or physical status requiring assistance for treatment of hypoglycemia, irrespective of glucose level |
Clinical Significance of Each Level
Level 1 Hypoglycemia
- Represents the threshold for neuroendocrine responses to falling glucose in people without diabetes 1
- Considered clinically important regardless of symptoms 1
- May trigger adrenergic symptoms including shakiness, irritability, tachycardia, sweating, and hunger 1
- Should prompt consideration of treatment plan adjustment, especially if recurrent 1
Level 2 Hypoglycemia
- Threshold at which neuroglycopenic symptoms begin to occur 1
- Requires immediate action to resolve the hypoglycemic event 1
- May indicate impaired hypoglycemia awareness if occurring without symptoms 1
- Warrants investigation and review of the treatment plan 1
Level 3 Hypoglycemia
- Severe event requiring assistance from another person 1
- May involve altered mental status, loss of consciousness, seizures, or coma 2
- Considered an urgent medical issue requiring intervention 1
- May progress to death if not treated promptly 2
Symptoms of Hypoglycemia
Hypoglycemic symptoms fall into two categories:
Adrenergic (Autonomic) Symptoms
- Shakiness/tremor
- Sweating
- Tachycardia/palpitations
- Hunger
- Anxiety/nervousness
- Irritability 2
Neuroglycopenic Symptoms
- Confusion/disorientation
- Weakness/fatigue
- Dizziness
- Blurred vision
- Difficulty concentrating
- Slurred speech
- Headache 2
Clinical Implications
Hypoglycemia is often the major limiting factor in the glycemic management of both type 1 and type 2 diabetes 1. Many people with diabetes demonstrate impaired counterregulatory responses to hypoglycemia and/or experience impaired hypoglycemia awareness, making any measured glucose level <70 mg/dL clinically important regardless of symptoms 1.
Recurrent level 2 hypoglycemia and/or level 3 hypoglycemia constitutes an urgent medical issue requiring intervention with medical treatment plan adjustment, behavioral intervention, and delivery of diabetes education 1.
High-Risk Populations
Individuals at particularly high risk for hypoglycemia include:
- Those with recent (within 3-6 months) level 2 or 3 hypoglycemia
- Patients on intensive insulin therapy
- Those with impaired hypoglycemia awareness
- Patients with end-stage kidney disease
- Those with cognitive impairment or dementia 1
Social determinants that increase risk include food insecurity, low-income status, housing insecurity, and fasting for religious or cultural reasons 1.
Understanding the definition and classification of hypoglycemia is essential for appropriate clinical management and prevention of this potentially life-threatening complication of diabetes treatment.