Insulin Infusion Should Be Prepared with 0.9% Sodium Chloride Solution
Insulin infusions should only be prepared with 0.9% sodium chloride (normal saline) solution, not with dextrose-containing fluids, to ensure accurate blood glucose monitoring and prevent medication errors.
Recommended Insulin Infusion Preparation
- Insulin infusions should be prepared using only 0.9% sodium chloride (normal saline) solution as the diluent, as specified in the FDA drug labeling for intravenous insulin administration 1
- For intravenous use, insulin should be used at concentrations from 0.1 unit/mL to 1 unit/mL in infusion systems with 0.9% sodium chloride using polyvinyl chloride infusion bags 1
- Sodium chloride 0.9%, with or without heparin, should be the only solution used for arterial line infusion and flushing to prevent sample contamination errors 2
Rationale for Using Normal Saline
- Using glucose-containing solutions as insulin diluents can lead to dangerous sampling errors when monitoring blood glucose levels 2
- Even minimal contamination of blood samples with glucose-containing solutions can conceal true hypoglycemia or make a normal sample appear hyperglycemic, potentially leading to inappropriate insulin therapy 2
- With sodium chloride 0.9% flush, only gross sample contamination will cause dangerous sampling errors, making it the safer option 2
Stability of Insulin in Normal Saline
- Insulin at a concentration of 1 unit/mL in 0.9% sodium chloride is stable for up to 336 hours (14 days) when stored at 2°C-8°C (36°F-46°F) 3
- Higher concentrations of insulin (16 units/mL) in 0.9% saline solution remain within 90% of equilibrium concentration for 14 days, both when refrigerated and at room temperature 4
- Pretreatment of polyvinyl chloride administration sets with sodium chloride solution can reduce insulin sorption by half, improving delivery efficiency 5
Preventing Medication Errors
- Hospitals must have policies that define local procedures for arterial line use, including prescribing, administering, and monitoring flush solutions 2
- The flush solution must be independently double-checked by a second practitioner before setting up and attaching to an arterial line 2
- All staff involved in the insertion, management, or sampling from arterial lines must be appropriately trained to prevent sample contamination errors 2
Monitoring Considerations
- Fatal neuroglycopenic brain injury can occur within two hours of the onset of hypoglycemia, making accurate glucose monitoring critical 2
- Erratic or highly varying sequential glucose test results should heighten the suspicion of blood sample contamination error 2
- When using closed arterial line systems, the risk of significant contamination of blood samples is effectively eliminated 2
Common Pitfalls to Avoid
- Never use glucose-containing solutions (like 5% dextrose) as insulin diluents or arterial line flush solutions, as they can lead to inaccurate glucose readings and inappropriate insulin dosing 2
- Avoid storing glucose-containing solutions in clinical areas where they might be mistakenly used as flush solutions 2
- Be aware that contamination of a blood sample with just 0.03 mL of glucose 5% solution would conceal true hypoglycemia or make a normal sample hyperglycemic 2
While some older research suggests that adding protein (like polygeline) to insulin carrier solutions may minimize insulin adsorption to containers 6, 7, current FDA guidelines and more recent evidence support the use of normal saline as the standard diluent for insulin infusions 1, 3.