How Do You Give Intravenous Insulin Therapy?

IV insulin is administered as an emergency procedure; it is dangerous and must be done under supervision of a doctor.

Intravenous insulin therapy is a treatment procedure to control high blood sugar (hyperglycemia) in ICU patients. Rapid and efficient control of hyperglycemia improves recovery rates and reduces mortality in critically ill patients.

Intravenous insulin therapy is performed only under medical supervision along with continuous monitoring of blood sugar levels and other vital parameters. 

Self-administration of insulin by people with diabetes is always an injection in the fatty tissue under the skin (subcutaneous), and never intravenous.

Intravenous insulin therapy for managing hyperglycemia requires a well-coordinated protocol in place and combined effort from the various health professionals in the hospital.

• The treating physician determines when IV insulin therapy should be started in consultation with the endocrinologist.
• The nurse administers the IV insulin and monitors the patient’s sugar levels with measurements at set intervals.
• The dosage is continually adjusted (titrated) based on the patient’s sugar levels.
• The patient is weaned from intravenous insulin at the appropriate time.

Most hospitals follow an established protocol for hyperglycemia management in ICU patients, though there may be minor variations in protocols.

An ideal insulin protocol aims at achieving the target glucose levels within a short period and maintaining them within that range. Glucose levels of below 70 mg/dl is considered hypoglycemia, and persistent levels of 200 mg/dl is hyperglycemia.

A safe and effective IV insulin protocol incorporates the following:

• Determines the appropriate glucose level target
• Defines the hyperglycemic threshold to start treatment
• Provides clear directions for monitoring the glucose levels and titrating the dosage based on changes in the levels
• Plans for transition to subcutaneous insulin

Many institutions have developed and implemented intravenous insulin protocols based on clinical experience. Most IV insulin protocols are significantly similar, though differences exist in factors such as:

• Treatment in the presence and absence of pre-existing diabetes
• Initial hyperglycemic threshold to start treatment
• Calculation of initial bolus (rapid-acting) insulin dose
• Calculation of subsequent doses and changes based on
  • sugar levels
  • insulin resistance
• Target glucose level

Over 20 protocols are in use, and the following sections outline two archetypal intravenous insulin protocols.

Also known as Davidson or Glucommander Protocol, the Georgia Hospital Protocol’s glucose control target is 140-180 mg/dl. The Glucommander Protocol is a computer-directed system that dynamically determines the dosage, timing and titration of insulin based on blood glucose levels and rate of change in the levels.

The steps followed in the protocol include the following:

• Insulin infusion
• Discontinuation of previous diabetes medications
• Obtaining the patient’s metabolic profile
• Checking initial blood glucose level
• Regular human insulin is mixed with normal saline before administration
• After initiation of IV infusion, glucose levels are checked every hour
• Glucose level testing is reduced to every 2 hours if target range is stable for 4 consecutive readings
• Administration of dextrose in case of hypoglycemia and glucose level test is done every 15 minutes until the glucose level stabilizes

Glucose Readings that Prompt a Physician Alert

Glucommander Protocol is a simple system that can be administered by a trained nurse. Glucose levels and potassium levels are regularly monitored. The nurse notifies the physician if:

• Glucose level is less than 60 mg/dl for two consecutive readings
• Glucose level is more than 200 mg/dl for two consecutive readings
• Insulin requirement exceeds 24 units/hour
• Patient’s potassium level drops below 4 mmol/L
• Continuous enteral feeding (through nasal tube), parenteral nutrition (through the vein) or insulin infusion is stopped or interrupted

Transition to Subcutaneous Insulin

• Glucose levels should be within target range for at least four hours before discontinuing IV insulin
• Subcutaneous insulin dosage is calculated and initiated
• IV infusion of insulin continues for two hours after starting subcutaneous insulin therapy

The Portland Protocol targets a glucose level of 125-175 mg/dl and is started for all ICU patients if glucose level is more than 150 mg/dl, even if “nondiabetic.” Dosage of insulin is based on blood glucose levels, and is changed in proportion with change in levels. A chart specifies the dosage and their adjustments in relation to changes in glucose levels.

The Portland Protocol involves the following steps:

• Blood glucose level check upon admission
• Hemoglobin A1c (HbA1c) measurement is taken
• Regular human insulin is mixed with normal saline before administration
• Intravenous insulin is initiated and blood glucose level checked every two hours
• Dextrose is administered in case of hypoglycemia
• If bedside measurement of glucose shows a level below 40 mg/dl or above 450 mg/dl, a confirmatory laboratory glucose test is done

Protocol Duration

• All patients who remain hyperglycemic should continue the protocol throughout the ICU stay.
• Nondiabetic, euglycemic (normal sugar level) patients can stop the protocol if target level is maintained with less than half a unit of insulin. The glucose level will be monitored for 24 hours and if the level goes above 150 mg/dl, the insulin protocol will be resumed.
• If diabetic patients continue to need insulin after three days post-surgery, and if their HbA1C is higher than 6% at admission time, further treatment will be designed in consultation with the endocrinologist.