Elneopa NF No. 1 and No. 2 infusions are complete parenteral nutrition solutions packaged as four-chambered bags. They have been used for home parenteral nutrition, with insulin injected into the bags for patients whose blood glucose becomes elevated. In this study, the stability of insulin in No. 1 and No. 2 bags was investigated. The quantity of insulin in Elneopa NF No. 2 was signiˆcantly lower than that in Elneopa NF No. 1. When insulin was injected into the upper chamber of either product, decreases in insulin levels were not observed. In contrast, the levels of insulin injected into the lower chamber of both products signiˆcantly decreased, with a larger diŠerence in Elneopa NF No. 2. As the amino acid content is diŠerent between No. 1 and No. 2, amino acids may be considered a potential cause for the degradation of insulin in the bags. In addition, decreases in insulin levels were observed as the solutions passed through infusion sets just after ‰ushing began, with both Elneopa NF No. 1 and No. 2. In conclusion, the concentration of insulin injected into the Elneopa infusion bags decreases, especially in No. 2 bags, and insulin is absorbed by the infusion sets.