Can Insulin Overdose Cause a Heart Attack? Risks and Management

Managing diabetes demands precision, particularly with insulin therapy, which is vital for regulating blood sugar in both Type 1 and Type 2 diabetes. Insulin maintains glucose control and prevents complications, but taking too much—whether accidentally or intentionally—can lead to serious health risks.

This stresses the cardiovascular system and potentially leads to a heart attack. Thus, although it indirectly elevates heart-attack risks, the answer to ‘Can Insulin Overdose Cause a Heart Attack?’ is technically a ‘no’. The connection isn’t direct, but it involves the effects of hypoglycemia (low blood sugar), cardiovascular stress, and pre-existing heart conditions. This article explores what occurs during an insulin overdose, its symptoms, and its potential impact on heart health.

What Is an Insulin Overdose?

An insulin overdose happens when someone takes more insulin than their body requires. This can result from:

• Skipping meals after an insulin injection
• Incorrect dosing or timing errors
• Mixing up insulin types (e.g., short-acting vs. long-acting)
• Intentional overuse, in rare cases, related to self-harm

Excess insulin lowers blood sugar excessively, leading to hypoglycemia. Mild cases may cause discomfort, but severe hypoglycemia can escalate into a medical emergency.

How Insulin Works—and how overdose becomes dangerous

• Normal action: Insulin helps cells take in glucose for energy.
• Overdose: Excess insulin causes a sharp drop in blood sugar (hypoglycemia)—the crux of all dangerous effects.
• In non-diabetics or obese individuals using insulin wrongly, this same drop can be abrupt and severe, leading to hypoglycemia.

Insulin Overdose and Its Impact on the Heart

Can an insulin overdose lead to a heart attack? Here’s how they’re connected:

• Adrenaline Surge from Hypoglycemia: When blood sugar plummets due to excess insulin, the body releases stress hormones like adrenaline (epinephrine). This spikes heart rate and blood pressure, straining the cardiovascular system.

• Risk of Arrhythmias: Severe hypoglycemia can interfere with the heart’s electrical activity, potentially causing irregular heart rhythms (arrhythmias) that may lead to cardiac arrest.

• Increased Heart Attack Risk in At-Risk Individuals: For those with pre-existing heart conditions, the stress of severe hypoglycemia heightens the likelihood of a myocardial infarction (heart attack).

While insulin itself doesn’t directly harm the heart, an overdose triggering extreme hypoglycemia can create conditions that elevate the risk of a heart attack.

Symptoms of Insulin Overdose

Following are the common signs of mild to severe low sugar levels:

Mild-to-moderate hypoglycemia

• Anxiety, irritability, confusion, “brain fog”
• Tremors, shakiness, weakness, dizziness
• Rapid heartbeat (tachycardia), sweating, chills
• Blurred or double vision

Severe hypoglycemia

• Seizures, disorientation, unconsciousness or coma
• Risk of irreversible neurological damage or death.

If you learn more about the overdose symptoms beyond heart disease, learn this expert’s guide on insulin overdose symptoms.

Fatality from Insulin Overdose

From the MDPI systematic review, 109 documented fatal cases of insulin or hypoglycemic-agent overdose worldwide:

• Suicide: ~65% (71 cases)
• Accidental: ~23% (25 cases)
• Homicide: ~12% (13 cases).

From South Australia data (approximate estimate), 40 fatal overdoses were identified over 2000–2019, averaging 2 deaths per year.

How Much Insulin Can Be Fatal?

There is no universally fatal dose of insulin, as the risk depends on several factors, including the type of insulin, individual body mass, insulin sensitivity, timing of administration, and the speed of medical intervention. Reported fatalities from insulin overdose vary widely: some cases have involved as little as 20 units, while others required 400 to 900 units or more. Because of these variations, even seemingly small mistakes in insulin dosing can be dangerous, highlighting the importance of careful administration and immediate medical attention in case of an overdose.

Insulin Overdose By Type

• Rapid-acting insulin (e.g., lispro, aspart): Quick onset, risk of swift hypoglycemia.

Normal consumption: Usually called as bolus insulin, this is also known as mealtime insulin. Consumed with the meals, the dosage can depend on the number of carbs you are going to consume, e.g., as 1 unit of rapid insulin usually is enough for 10 grams of carbs, consuming a meal with 50 grams of carbs would require 5 units of rapid insulin.

• Long-acting insulin (e.g., glargine, detemir, degludec): Delayed, prolonged hypoglycemia—can lurk for hours to days.

Normal consumption: Consumed once a day, this is usually recommended based on your weight, the average dose of this insulin is often 10 units a day, which can be increased by 2 – 4 units every 3 days. According to the WebMD, this may continue until the target of 80 to 130 mg/dL during fasting is achieved.

Important:

Fatal outcomes have been reported across all types. Insulin type is not the only thing to be concerned about, but you need to be vigilant about route, timing, and NOT repeating a dose when you do not need it. If you have missed a dose and the time for next insulin dose is close, do not consume the last dose as it may double up the results.

Scientific Research and Studies

Several studies have explored the connection between insulin overdose, hypoglycemia, and cardiovascular events:

• Research published in the American Diabetes Association (ADA) journals shows that severe hypoglycemia is associated with higher cardiovascular mortality.
• Clinical evidence suggests that low blood sugar episodes increase the risk of arrhythmias, especially at night.
• A 2018 study found that patients with Type 2 diabetes who experienced frequent hypoglycemia had a higher incidence of cardiovascular complications.

These findings confirm that while not every insulin overdose causes a heart attack, the risk increases significantly in people with heart disease.

Who Is at Greater Risk from an Insulin Overdose?

Certain individuals face a higher risk of heart-related complications from an insulin overdose. These include:

• Type 1 diabetes patients using intensive insulin regimens
• Type 2 diabetes patients with pre-existing heart disease or hypertension
• Older adults with weakened cardiovascular systems
• Individuals with kidney disease, which impairs insulin clearance
• People with hypoglycemia unawareness, who may miss early warning signs

For these groups, even a moderate insulin overdose can place significant stress on the heart, increasing the risk of serious complications.

Required Steps in Case of Insulin Overdose

Stay calm, act fast and do the following:

Typical Hypoglycemia Symptoms:

Follow 15:15 rule in this condition and keep monitoring.

• Consume 15 g of fast-acting carbs (juice, glucose tabs, candy, honey).
• Wait 15 min, then re-check blood sugar; repeat if still low.

You may want to have a look at Trueplus Glucose Gel and Shots here at CGM Monitors.

Prevention Tips for Safe Insulin Use

• Always double-check your dose, type, and timing before injecting.
• Do not consume the missed dose near the next dose.
• Avoid distractions while dosing.
• Educate family/friends on your hypoglycemia signs and emergency steps.
• Wear a medical alert bracelet specifying insulin use & CGM Monitors monitoring for rapid detection.

Summary

• Insulin overdose doesn’t directly cause heart attack, but hypoglycemia can increase cardiac risk in vulnerable individuals.
• Symptoms range from mild (sweating, shakiness) to severe (seizure, coma).
• No fixed lethal dose—fatal outcomes have occurred at doses as low as 20 units, up to thousands.
• Post-mortem data: ~65% suicides, ~23% accidental, ~12% homicides of 109 total documented cases.
• Immediate treatment and prevention are key.

Frequently Asked Question