Intravenous (IV) insulin therapy is a method of delivering insulin directly into someone’s bloodstream. Healthcare professionals may use IV insulin to treat people with high blood sugar levels.

High blood sugar occurs when the body is unable to control blood sugar levels properly using insulin. Insulin is a hormone that allows cells to absorb glucose from the bloodstream. Glucose is an energy source for the body. Blood sugar is another name for glucose in the blood.

High blood sugar levels can be life threatening without treatment. Doctors refer to high blood sugar levels as hyperglycemia. IV insulin therapy is a treatment for hyperglycemia.

Read on to learn more about IV insulin therapy and its possible complications.

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IV insulin therapy is a treatment that healthcare professionals administer in hospitals. They use IV insulin therapy to reduce blood sugar levels in people with hyperglycemia.

IV insulin therapy involves feeding insulin directly into someone’s bloodstream through a thin tube in a vein. This extra insulin encourages the body’s cells to absorb excess glucose in the bloodstream.

IV insulin therapy is a quick way of getting insulin into the bloodstream. Its fast-acting nature makes IV insulin therapy a useful treatment for hyperglycemic emergencies.

Hyperglycemia is common in people with diabetes. However, IV insulin therapy is also useful for treating hyperglycemia due to:

  • diabetic ketoacidosis
  • hyperosmolar states
  • medical or surgical critical care
  • heart conditions, such as myocardial infarction or cardiogenic shock
  • childbirth
  • organ transplant
  • stroke
  • high dose glucocorticoid therapy
  • feeding via tube or IV
  • hyperkalemia

Doctors traditionally only used regular human insulin — a synthetic form of insulin — in IV insulin therapy.

However, research from 2015 indicates that insulin aspart IVs were beneficial when treating people following heart surgery. Insulin aspart is another synthetic form of insulin that scientists developed to be fast acting. Another fast-acting synthetic insulin that could be useful is insulin lispro.

However, any form of insulin becomes fast acting when using IV injections.

A doctor may consider the following factors when determining the right type of insulin for IV insulin therapy:

  • the type of condition or disease
  • the duration of IV insulin therapy
  • the type of insulin someone will need after completing IV insulin therapy

IV insulin enters straight into the bloodstream and only lasts a few minutes. This means someone may require several hours of IV insulin therapy before their blood sugar levels return to normal.

IV insulin therapy involves inserting a thin tube, which doctors refer to as a catheter, into the arm. The doctor will attach the catheter with a needle that goes directly into a vein. The catheter is also attached to a bag that contains insulin and other liquids, such as saline.

The amount of time a person requires IV insulin therapy can depend on their blood sugar levels. IV insulin therapy can last anywhere between 3–12 hours. Healthcare professionals will monitor the person’s blood sugar levels throughout this time to keep the levels from dropping too low.

Doctors refer to abnormally low blood sugar levels as hypoglycemia. Hypoglycemia can cause other health problems.

People receiving IV insulin treatment will need to transition to subcutaneous insulin after their blood sugar levels become normal. Proper care is necessary during this process to keep blood sugar levels in a healthy range.

The point when a person may transition from IV insulin therapy to subcutaneous insulin may depend on:

  • the severity of their condition
  • whether they were using insulin before the IV insulin treatment
  • when they can orally consume food again

Research from 2014 suggests the transition from IV insulin to subcutaneous insulin should begin once a person can consume food orally and has stable blood sugar levels. IV insulin should continue for 1–2 hours after administering subcutaneous insulin.

A 2016 study states someone should receive 50–59% of their previous 24-hour insulin intake when transitioning to subcutaneous insulin. However, the researchers note that further study is necessary to determine the safety and effectiveness of this level of subcutaneous insulin.

The protocol for determining how much IV insulin a person should receive can vary among hospitals. Information from the American Diabetes Association suggests that hospitals consider the following factors when determining the best protocol to use:

  • appropriate blood sugar targets
  • time frame available for treatment
  • ease and practicality of monitoring
  • clarity of the monitoring instructions
  • risk of hypoglycemia
  • effectiveness
  • the plan for transitioning to subcutaneous insulin

The organization also suggests that optimal blood sugar levels should be between 140–180 milligrams per deciliter (mg/dl) for most people. However, some people may require a lower blood sugar level of 110–140 mg/dl.

IV insulin therapy can carry certain risks, such as hypoglycemia. Symptoms of hypoglycemia include:

  • shakiness or jitters
  • hunger
  • tiredness
  • dizziness, lightheadedness, or confusion
  • rapid or unstable heartbeat
  • headache
  • inability to see or speak clearly
  • loss of consciousness
  • seizure

Healthcare professionals use IV insulin therapy to treat people with hyperglycemia. The condition can be due to diabetes or other problems, such as heart disease.

IV insulin therapy involves supplying insulin directly into the bloodstream through a catheter. Healthy blood sugar levels are between 140–180 mg/dl for most people. However, some people require lower levels than this. Doctors will carefully monitor for hypoglycemia during IV insulin therapy.