@sally2026 you choose when to change the medication. The syringe holds 10 cc of medication. It depends how the doctor sets you up how long it will last. The pump has a loading dose to start you off and the 3 settings of low (often used at nighttime), the base rate which normally is used most of the time, and a high setting when you need extra while exercising. There is one more extra dose that the doctor can program if you need an extra boost right away which can be set how often the Dr feels you might need it. I have found it very flexible and when you are on high doses it relieves you of having to take it every couple hours check with your doctor and see if they think it would be easier to get your husband set up in a routine. She wouldn’t have to remember to take it every few hours it would automatically run for him.