In insulin infusion pumps If the cartridge or the device containing the cartridge is dropped, damaged or crushed, there is a risk of leakage of insulin If it hasn’ t been stored correctly or if it has been frozen (see 6 How to store NovoMix 30) If the insulin is not uniformly white and cloudy when it’ s mixed If clumps of material are present or if solid white particles stick to the bottom or the wall of the cartridge giving a frosted appearance.