What Is Intravenous Insulin Therapy?

Intravenous insulin is only administered in a diabetic or other emergency; people with diabetes administer their daily insulin doses subcutaneously.

Intravenous insulin therapy is a treatment procedure to manage high blood sugar (hyperglycemia) with intravenous infusion of insulin. Intravenous insulin is administered only in a hospital ICU setting in selected critically ill patients with a diabetes emergency or other conditions affecting blood sugar who require rapid and efficient control of hyperglycemia.

Self-administration of insulin by people with diabetes is always with an injection in the fatty tissue under the skin (subcutaneous). Intravenous insulin therapy is performed only under medical supervision along with continuous monitoring of blood sugar levels and various other vital parameters.

The only type of insulin that is given intravenously is human regular insulin. A rapid-acting insulin analog is unnecessary in intravenous insulin administration because the insulin is delivered directly into the bloodstream and takes immediate effect.

An insulin analog is human insulin genetically altered in the laboratory to make them rapid-acting or long lasting. A rapid-acting analog insulin may be used to increase the insulin absorption rate in subcutaneous insulin.

Intravenous insulin acts rapidly and lasts for a very short duration in the body. To maintain the desired glucose levels in the blood, insulin is infused continuously with appropriate dosage titrations depending on the blood sugar level.

The potential uses for intravenous insulin therapy for treatment of hyperglycemia in patients under critical care include the following conditions:

• Heart-related conditions such as:
  • Post-cardiac surgery
  • Myocardial infarction
  • Cardiogenic shock
• Diabetic ketoacidosis (high level of acidic substances known as ketones in the blood)
• Hyperglycemia and hyperosmolarity (high concentration of dissolved electrolytes in blood)
• Medical or surgical critical care
• Patients on enteral (feeding tube) or parenteral (nutrition through veins) feeding for prolonged periods
• During labor and delivery
• Patients on high dose glucocorticoid therapy
• Post organ transplantation
• Stroke
• To determine the dosage before transition to subcutaneous insulin

Both American Diabetes Association (ADA) and American College of Endocrinology recommend that the target blood glucose range should be 140-180 mg/dl for the majority of the patients. A target of 110-140 mg/dl may be appropriate for some patients if it can be achieved without causing significant hypoglycemia.

Hypoglycemia is the primary adverse effect of intravenous insulin therapy. Successful implementation of IV insulin therapy while preventing hypoglycemia heavily depends on accurate bedside measurement of the glucose levels. Hospitals rely on point-of-care testing with portable monitors because of the requirement for frequent testing.

Bedside glucometers are more accurate in normal blood sugar range but in hyper or hypoglycemic patients, glucometers may vary up to 20% from lab results. Factors that affect bedside glucose measurement include:

• Operator errors such as improper calibration or use
• Source of blood (serum, plasma or whole blood)
• Blood sampling site (capillary, vein or artery)
• Amount of blood
  • Excess blood can show false high reading
  • Inadequate blood can show false low reading
• Anemia can show false high level in whole blood test
• Peripheral hypoperfusion (reduced blood flow) from:
  • Shock
  • Blood vessel constriction
  • Arterial spasms
  • Dehydration
• Delay in processing of blood sample

Certain medications and other substances in the bloodstream can interfere with the glucose measurements, which include

• Levodopa
• Dopamine
• Mannitol
• Acetaminophen
• High unconjugated bilirubin
• Severe lipemia (high concentration of emulsified fat in blood)
• High uric acid
• Maltose (found in immunoglobulin solutions)
• Icodextrin (found in peritoneal dialysis fluid)