Intravenous Insulin Therapy. Brief introduction

Intravenous insulin therapy is a treatment procedure aimed 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 in 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.

Insulin is the preferred treatment modality in the hospital setting because it is the most potent agent to lower blood glucose. It is rapidly effective, easily titrated, has no absolute contraindications [https://pubmed.ncbi.nlm.nih.gov/20689148/]. However, insulin is a high-alert medication that is consistently implicated in reports of preventable patient harm (from hypoglycemia) and thus requires accurate monitoring and standardized protocols to minimize risks while maximizing benefits [http://www.jointcommission.org/sentinel_event_alert_issue_11_high-alert_medications_and_patient_safety].

Intravenous (IV) infusion is the preferred route of insulin delivery in critical care, labor and delivery, and perioperative inpatient settings. The rapid onset and short duration of action associated with IV infusion allow for matching insulin requirements to rapidly changing glucose levels. Sliding-scale or correction algorithms with regular or rapid-acting insulin administered as needed for hyperglycemia without scheduled basal insulin or prandial insulin (for patients who are eating) are outdated treatment modalities that should be abandoned. Data are lacking to support the benefit of sliding-scale insulin or correction insulin algorithms without basal insulin, and these practices are associated with wide fluctuations in blood glucose, which have been linked to higher hospital mortality rates [https://www.ncbi.nlm.nih.gov/pubmed/15372839/].

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 a human insulin genetically altered in the laboratory to make it rapid-acting or long-lasting. 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 time 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 the 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 the 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 transitioning to subcutaneous insulin.

Insulin infusion may be an alternative to a basal-bolus insulin regimen outside the critical care setting for perioperative and other patients who are not eating (NPO status) and patients whose glycemia is poorly controlled with subcutaneous insulin. Insulin infusion can be safely administered outside the critical care setting if provided staff education, nurse-to-patient ratios, and blood glucose monitoring are adequate [https://www.ncbi.nlm.nih.gov/pubmed/15828597/]. In addition, setting more moderate glycemic targets for patients outside the critical care setting may minimize the nursing time for blood glucose monitoring and titration of the insulin infusion. For patients starting parenteral or enteral nutrition, the use of IV insulin infusion with appropriate monitoring may allow for more rapid titration and determination of patients’ insulin requirements than one could expect from either a subcutaneous insulin regimen or from the practice of including insulin in the parenteral nutrition solution. The use of IV insulin infusion in patients who are eating or are receiving intermittent enteral/parenteral nutrition requires proactive increases in infusion rate with the start of nutritional intake and decreases when nutritional intake is stopped, and thus, in most situations, conversion to subcutaneous insulin is appropriate because it is less labor-intensive.