Hypoglycemia unawareness
Formal Definition
A life-threatening complication of insulin therapy in which the patient loses the adrenergic warning symptoms of hypoglycemia (tremor, sweating, palpitations, anxiety, hunger) due to blunted counter-regulatory hormone responses from recurrent episodes of hypoglycemia, leaving the patient vulnerable to severe hypoglycemic events (seizures, coma, death) without premonitory symptoms; often requires custom target glucose ranges higher than standard to allow the autonomic symptoms to recover.
How It's Used on the Ward
"Hypoglycemia unawareness" — the patient doesn t feel their lows anymore and can go from normal to confused or unconscious without warning; the body s alarm system for hypoglycemia has been broken by repeated lows; a CGM with low alarms is critical for safety.
Example
""61-year-old Type 1 diabetic on insulin pump with 4 hypoglycemic episodes in the past 6 months, 2 requiring ED visits and one EMS call when she was found unconscious. She reports never feeling shaky or sweaty before her sugar drops — just sudden confusion. CGM data shows 14% of time below 70 mg/dL, including overnight events she doesn t wake up for. Diagnosis: hypoglycemia unawareness with defective counter-regulatory response. Target glucose raised from 80-130 to 100-150. CGM low alert set at 90 mg/dL. Education on avoiding lows for several weeks to allow autonomic symptom recovery.""
Clinical Context
Mechanism: recurrent hypoglycemia → reduced counter-regulatory hormone response (diminished glucagon, epinephrine, cortisol response) + blunted sympathetic neuropathy → loss of adrenergic warning symptoms. Risk factors: long duration T1DM, tight glycemic control (HbA1c <7%), frequent hypoglycemia, autonomic neuropathy, beta-blockers (mask adrenergic symptoms). Management: raise target glucose range for 2-4 weeks (avoid all hypoglycemia to allow recovery of symptoms), CGM with audible low alerts, structured insulin pump with suspend-on-low, consider continuous glucose monitoring with predictive low alert. Avoid tight control in this population — the hypoglycemia danger outweighs marginal A1c benefit. Patients should carry glucagon kit (dasiglucagon or Baqsimi) and wear medical alert.