Emergency: Severe Hypoglycemia with Altered Consciousness

Rapid Assessment

Background Risk Context (Important)

• CABG / CVD: Hypoglycemia causes catecholamine surge, increasing risk of arrhythmia, demand ischaemia, and plaque rupture - especially critical post-CABG
• CVA: Hypoglycaemia can mimic or preciprocate stroke; focal deficits may appear and can mislead
• HTN on antihypertensives / T2DM on sulphonylureas or insulin: Both blunt adrenergic warning symptoms (hypoglycaemia unawareness)
• Beta-blockers (common post-CABG): Mask tachycardia, the earliest autonomic warning sign

Patients on beta-blockers with autonomic neuropathy may have no prodrome and present directly in coma - Clinical Anesthesia, Barash et al.

Immediate Management - DO NOW

Step 1: Airway, Breathing, Circulation

• Position patient safely (lateral if unconscious)
• Ensure patent airway; apply O2 if SpO2 < 94%
• IV access - TWO large bore lines

Step 2: Draw blood BEFORE giving glucose (if possible)

• Blood glucose (confirm CBG)
• Serum electrolytes, renal function, LFT
• Full blood count
• Blood culture if sepsis suspected
• Serum insulin + C-peptide (if cause unclear)
• ABG

Step 3: Glucose Correction (PRIORITY)

"In other patients, after blood is drawn for glucose determination, 1 to 3 ampules of D50W administered IV... Augmentation by D50W may range from <40 mg/dL to >350 mg/dL." - Rosen's Emergency Medicine

"Treatment of hypoglycemia is with 25 g of IV dextrose (50 mL of dextrose 50% in water)... goal is to achieve blood glucose above 100 mg/dL." - Clinical Anesthesia, Barash et al.

• D50W (50% Dextrose): 1-2 ampules (50-100 mL) IV push over 2-5 minutes
• If D50W unavailable: D10W 250 mL IV bolus (equivalent glucose load)
• Recheck CBG in 15 minutes

Step 4: If IV access fails

• Glucagon 1 mg IM or SC - onset 10-20 minutes, peak at 30 min
• Note: Glucagon less reliable if patient is malnourished or has depleted glycogen stores

Step 5: Maintenance after correction

• Start 10% Dextrose (D10W) infusion at 100 mL/hr after bolus
• Recheck CBG every 15-30 minutes until stable >100 mg/dL
• Target glucose: 100-180 mg/dL in this high-CV-risk patient

Step 6: Thiamine 100 mg IV

• If alcohol use, poor nutrition, or prolonged hypoglycemia suspected
• Give BEFORE or WITH glucose to prevent Wernicke's encephalopathy

Cause Identification (Critically Important)

1. Insulin overdose - check last dose, timing, type
2. Sulphonylurea excess (glibenclamide, glipizide) - can cause prolonged, recurrent hypoglycaemia - observe 24 hours minimum
3. Missed meal / reduced oral intake with usual dose
4. Renal impairment - prolongs action of insulin and OHAs
5. Drug interaction - fluoroquinolones, beta-blockers, aspirin can potentiate hypoglycaemia
6. Post-CABG change in medications or diet pattern

"Patients with overdose of sulphonylurea hypoglycemic agents should be observed for 24 hours if hypoglycaemia recurs in the ED after management." - Rosen's Emergency Medicine

Monitoring After Correction

• CBG every 15 minutes x 4, then every 30-60 minutes
• Continuous cardiac monitoring (ECG) - patient has CABG history, risk of ischaemia from catecholamine surge
• Neurological reassessment - if consciousness does not improve fully after glucose correction, suspect concurrent CVA, sepsis, or medication toxicity
• Watch for rebound hypoglycaemia especially if sulphonylurea was the cause

Differential Diagnoses (if no improvement after glucose correction)

• Acute CVA (haemorrhagic or ischaemic) - do urgent NCCT head
• Septic encephalopathy - look for fever, focus of infection
• Hypertensive encephalopathy (BP is controlled here, less likely)
• Drug toxicity / polypharmacy in elderly cardiac patient
• Hypoglycaemic brain injury - if CBG was critically low for prolonged time

Disposition

• Admit to HDU/ICU given CABG + CVA + altered sensorium
• Do NOT discharge even after correction if cause is sulphonylurea or if cause is unknown
• Endocrinology/diabetology review for medication adjustment
• Cardiology awareness given high CV risk

Why Thiamine? The Biochemical Reason

The Core Problem: Glucose Cannot Be Used Without Thiamine

Glucose
   ↓  (Glycolysis)
Pyruvate
   ↓  ← THIAMINE (B1) is the KEY COFACTOR here
Acetyl-CoA
   ↓
Krebs Cycle → ATP (energy for brain cells)

"Thiamine (vitamin B1) is a key cofactor for pyruvate dehydrogenase (PDH). The activity of PDH is diminished by the lack of thiamine, so the rate of regeneration of ATP in brain cells will not be sufficient for their biologic work. Therefore, glycolysis will be stimulated in the brain to make ATP. As a result, there will be a sudden rise in the production of H+ and L-lactate anions in areas of the brain where the metabolic rate is the most rapid." - Brenner & Rector's The Kidney

What Happens If You Give Glucose Without Thiamine?

1. You flood the system with glucose
2. Glycolysis surges to produce energy
3. Pyruvate piles up because PDH cannot work (no thiamine)
4. Pyruvate converts to lactate instead of entering Krebs cycle
5. Brain cells starve of ATP despite having glucose available
6. Wernicke's Encephalopathy develops - an irreversible brain injury
   • Triad: confusion + ophthalmoplegia + ataxia
   • Untreated mortality: 20%

Why Give Thiamine BEFORE or WITH Glucose?

Thiamine-dependent metabolic failure and tissue injury; untreated mortality 20% - Rosen's Emergency Medicine

Why Glucagon? The Mechanism

What Glucagon Does

Low Blood Glucose
       ↓
Alpha cells of pancreas → secrete GLUCAGON
       ↓
Glucagon binds liver receptors
       ↓
Activates Adenylyl Cyclase → ↑ cAMP → activates Protein Kinase A
       ↓
Simultaneously does 3 things in the liver:
  1. GLYCOGENOLYSIS - breaks down stored glycogen → glucose (fast, minutes)
  2. Inhibits glycogen synthesis (stops glucose being stored)
  3. GLUCONEOGENESIS - makes new glucose from amino acids, glycerol, lactate (slower)
       ↓
Glucose released into bloodstream → Blood glucose rises

"In the liver, glucagon acts via cAMP to stimulate glycogenolysis, inhibit glycogen synthesis, stimulate gluconeogenesis, and initiate synthesis of some gluconeogenic enzymes. All these actions promote formation of glucose for release into the bloodstream." - Medical Physiology, Boron & Boulpaep

Why Is It Used in Hypoglycaemia When IV Access Fails?

• Malnourished patients
• Alcoholics (depleted glycogen)
• Prolonged starvation / NPO patients
• Severe liver disease

Summary in One Table