Hypoglycemia Management in Critically Ill Patients

Hypoglycemia Classification and Definition

The American Diabetes Association defines low blood glucose (hypoglycemia) in hospitalized critically ill patients as Level 1 hypoglycemia at <70 mg/dL (3.9 mmol/L) but ≥54 mg/dL (3.0 mmol/L), Level 2 (clinically significant) hypoglycemia at <54 mg/dL (3.0 mmol/L), and Level 3 (severe) hypoglycemia as any level associated with altered mental or physical functioning requiring assistance 1
Level 1 Hypoglycemia is characterized by blood glucose <70 mg/dL (3.9 mmol/L) but ≥54 mg/dL (3.0 mmol/L), representing the point at which neuroendocrine counterregulatory responses begin in people without diabetes 1
Level 2 Hypoglycemia is defined as blood glucose <54 mg/dL (3.0 mmol/L), the threshold at which neuroglycopenic symptoms typically begin to occur, requiring immediate action to resolve the hypoglycemic event 1
Level 3 Hypoglycemia is characterized by altered mental and/or physical functioning requiring assistance from another person for recovery, regardless of the actual blood glucose level, emphasizing functional impairment rather than a specific glucose threshold 1

Blood glucose <100 mg/dL should trigger reassessment of the insulin regimen, as fasting glucose <100 mg/dL predicts hypoglycemia within the next 24 hours 2
Blood glucose <70 mg/dL (3.9 mmol/L) requires modification of the insulin regimen, unless the hypoglycemic event is easily explained by other factors such as a missed meal 2

Moderate hypoglycemia is defined as 2.3 to 3.9 mmol/L (41 to 70 mg/dL), and severe hypoglycemia is defined as ≤2.2 mmol/L (≤40 mg/dL) for research reporting purposes 5, 6
Episodes of hypoglycemia in the hospital should be documented in the medical record and tracked, including duration, associated symptoms, amount of glucose administered, and the next blood glucose concentration for severe hypoglycemia 2, 5, 6
Hypoglycemia should be reported separately as iatrogenic (related to insulin treatment) versus spontaneous (unrelated to insulin treatment) 5, 6