What is the fatality rate in untreated insulin overdose?

Fatality Rate in Untreated Insulin Overdose

Severe hypoglycemia from untreated insulin overdose has a high mortality rate, with death occurring within minutes to hours if left untreated, as permanent brain damage develops rapidly due to the brain's inability to meet its energy needs. 1

Mortality Risk Factors

The fatality risk from untreated insulin overdose is influenced by several factors:

• Patient characteristics that increase mortality risk:

  • Advanced age (≥75 years)
  • Multiple comorbidities
  • Cardiovascular disease
  • Renal insufficiency
  • Septic shock
  • Mechanical ventilation
  • Higher illness severity scores 1

• Overdose characteristics:

  • Type of insulin (long-acting analogs like glargine and detemir cause extremely prolonged effects, often lasting 48-96 hours) 2
  • Intentional vs. accidental (65% of overdose cases are suicides, 23% accidental, and 12% homicidal) 3
  • Time to treatment (delayed treatment significantly increases mortality risk)

Pathophysiology of Death

Untreated insulin overdose leads to:

1. Severe hypoglycemia causing:

   • Neuronal depletion/necrosis (29.1% of autopsy findings) 3
   • Cerebral edema in severe cases 1
   • Seizures and unconsciousness

2. Secondary complications:

   • Pulmonary edema (55.7% of autopsy findings) 3
   • Pulmonary congestion (41.8% of autopsy findings) 3
   • Electrolyte disturbances (hypokalemia, hypophosphatemia, hypomagnesemia) 4

Evidence on Mortality Rates

While specific percentages for untreated insulin overdose fatality are not clearly established in the available evidence, several indicators suggest high mortality:

• Hypoglycemia is independently associated with increased mortality risk (odds ratio 3.233,95% CI [2.251,4.644]; p < .0001) in critically ill patients, even with mild-moderate hypoglycemia (blood glucose 54-63 mg/dL) 1

• In ICU settings, hypoglycemia increased mortality rate approximately twofold, though one study found this not statistically significant (RR: 1.2, CI: 0.927-1.58, P = 0.221) 5

• In cases of intentional insulin overdose, prolonged dextrose infusion (up to 40 hours) is often required for survival 4

Treatment Implications

The high fatality risk of untreated insulin overdose underscores the importance of:

1. Immediate intervention with:

   • Continuous intravenous 10% or 20% glucose infusion
   • Frequent capillary blood glucose monitoring
   • In extreme cases, surgical excision of the insulin injection site (effective even days after overdose) 2

2. Monitoring for complications:

   • Electrolyte abnormalities
   • Neurological status
   • Cardiac function

Clinical Pitfalls

• Diagnostic challenges: Postmortem toxicology screening of insulin is difficult due to the chemical characteristics of insulin and challenges distinguishing between endogenous and exogenous insulin 6

• Treatment duration: The effects of long-acting insulin analogs can persist for 48-96 hours, requiring extended monitoring and treatment 2

• Rebound hyperglycemia: After treating the overdose, careful reintroduction of diabetes treatment is essential, especially in patients with type 1 diabetes 2

In conclusion, untreated insulin overdose carries an extremely high mortality risk with death occurring rapidly due to neurological damage from severe hypoglycemia, making immediate recognition and aggressive treatment essential for survival.