Which types of added substances may cause insulin detemir to degrade in Levemir Penfill 100 units/ml solution for injection in cartridge?

Added substances, such as medicinal products containing thiols or sulphites, may degrade insulin detemir in Levemir Penfill 100 units/ml solution for injection in cartridge, which must not be added to infusion fluids or mixed with other medicinal products.