What are the step-by-step treatment options for a patient who has intentionally overdosed on insulin (intravenous glucose, dextrose, glucagon, octreotide)?

Step-by-Step Treatment of Intentional Insulin Overdose

Immediately initiate continuous intravenous dextrose infusion as the cornerstone of therapy, with frequent glucose monitoring every 15-30 minutes initially, and consider octreotide as adjunctive therapy if hypoglycemia persists despite large dextrose volumes or if the patient has a functional pancreas at risk for rebound hypoglycemia.

Initial Emergency Management

Immediate Dextrose Administration

• Administer 50 mL of 50% dextrose (D50) as an immediate bolus if the patient presents with symptomatic hypoglycemia or blood glucose <70 mg/dL 1, 2
• Follow immediately with continuous IV dextrose infusion, typically starting with 10% dextrose solution 3, 1
• For severe cases, dual infusions of both 5% and 10% dextrose may be required simultaneously 1
• Concentrated dextrose solutions >10% require central venous access to prevent peripheral vein damage 4

Intensive Glucose Monitoring

• Monitor blood glucose every 15-30 minutes during the initial stabilization phase, then hourly once stable 3, 5
• Continue frequent monitoring for at least 24-48 hours, as long-acting insulin formulations (glargine, detemir) can cause hypoglycemia for >100 hours due to depot effects at injection sites 5, 2
• Expect prolonged hypoglycemia requiring days of continuous dextrose infusion 3, 5, 6

Adjunctive Pharmacological Therapy

Octreotide (Preferred Adjunct)

Octreotide should be initiated when hypoglycemia persists despite large dextrose volumes or when complications from fluid overload develop 3, 5

• Typical dosing: 50-100 mcg subcutaneously every 6-8 hours 3, 5
• Mechanism: Inhibits endogenous insulin secretion from the pancreas that occurs in response to exogenous dextrose administration, preventing rebound hypoglycemia 3, 5
• Particularly beneficial in non-diabetic patients with functional pancreatic beta cells who are at highest risk for dextrose-induced endogenous insulin release 3, 5
• Reduces total dextrose requirements and prevents complications like peripheral edema from massive fluid volumes 3
• Consider initiating 12-24 hours after overdose if hypoglycemia remains refractory 3, 5

Glucagon (Limited Role)

• Glucagon 1 mg IM or IV may be used for acute rescue in the pre-hospital or initial emergency setting 7, 1
• Dosing per FDA label: 1 mg (1 mL) for adults and children >25 kg; 0.5 mg (0.5 mL) for children <25 kg 7
• Major limitation: Glucagon depletes hepatic glycogen stores and becomes ineffective with repeated dosing 7, 1
• Not suitable for sustained management of prolonged insulin overdose 1
• May cause vomiting, requiring airway protection 4

Electrolyte Management

Critical Monitoring and Replacement

Monitor serum potassium, magnesium, and phosphate levels every 4-6 hours initially 6, 2

• Hypokalemia is the most common and dangerous electrolyte abnormality, as insulin drives potassium intracellularly 6, 2
• Hypomagnesemia and hypophosphatemia also occur frequently 6, 2
• Replace electrolytes aggressively but avoid overly aggressive potassium repletion, which can cause arrhythmias 4
• Monitor pH and consider metabolic derangements 1

Oral Carbohydrate Supplementation

• Provide liberal oral carbohydrate intake whenever the patient is alert and able to swallow safely 7, 2
• Oral glucose supplements should be given in addition to, not instead of, IV dextrose 1, 2
• Continue oral intake even after IV dextrose is discontinued to prevent recurrence 7

Duration of Treatment and Monitoring

Expected Timeline

• Rapid-acting insulin (aspart, lispro): Monitor for 12-24 hours minimum 3, 2
• Long-acting insulin (glargine, detemir): Monitor for 48-120 hours due to prolonged depot absorption 5, 2
• Massive overdoses (>1000 units) may require >100 hours of continuous dextrose therapy 1, 5

ICU Admission Criteria

• All intentional insulin overdoses require ICU admission for continuous glucose monitoring and dextrose titration 1, 5
• Patients with decreased Glasgow Coma Scale at presentation have the poorest prognosis 1
• Overall mortality from insulin overdose is 2.7%, with neurological damage possible from prolonged severe hypoglycemia 1, 6

Diagnostic Confirmation

Laboratory Testing

• Measure insulin and C-peptide levels simultaneously to confirm exogenous insulin administration 6
• Elevated insulin with suppressed C-peptide confirms exogenous insulin overdose 6
• Check liver enzymes, as elevation is common in insulin overdose 1, 6

Critical Pitfalls to Avoid

• Do not rely solely on glucagon for sustained treatment - it depletes glycogen stores and becomes ineffective 7, 1
• Do not underestimate duration of monitoring required - long-acting insulins can cause hypoglycemia for >4 days 5, 2
• Do not aggressively replace potassium above 2.5-2.8 mEq/L - this can precipitate fatal arrhythmias 4
• Do not discharge patients prematurely - rebound hypoglycemia can occur even after apparent stabilization 3, 5
• Do not forget psychiatric evaluation - all intentional overdoses require mental health assessment before discharge 6, 2

Special Considerations

Fluid Overload Management

• Large dextrose volumes (often >10 liters over days) can cause significant peripheral edema and volume overload 3
• This is a key indication to initiate octreotide therapy to reduce dextrose requirements 3
• Consider diuretics if clinically significant fluid overload develops 3

Co-ingestions

• Alcohol enhances insulin action and complicates management 1
• Screen for other drug overdoses, as polypharmacy overdoses are common 2