Welcome Andrea (and Milo, too!)...
First thing, you need to take a deep breath and know that Milo's disease is very manageable and both you and he will be fine.
Milo needs to be fed low carb wet food. Janet & Binky's food chart is here:
http://www.felinediabetes.com/diabetic-cat-diets.htm. You will find a number of brands and varieties that are low carb and far more economical than food purchased at the vet's office. Milo's BG level will drop just with a change of diet (some have reported a drop of 100+ just with a diet change).
We encourage people to home test. There is a great deal of information about home testing here:
http://www.felinediabetes.com/FDMB/viewtopic.php?f=14&t=287. No only will home testing give you peace of mind, but you will also determine very important information about Milo and his diabetes. You will be able to determine his nadir (the lowest BG level over 12-hours), whether or not he is experiencing a hypo incident, and whether an adjustment to his insulin dose is necessary. Also, you will be able to avoid having to take Milo to the vet for his BG curves, as you will be able to do them yourself and provide the information to the vet.
Speaking of hypo incidents, there are some things you will need to have on hand in the vent of a hypo. Please see here
http://www.felinediabetes.com/FDMB/viewtopic.php?f=14&t=2354 and here
http://www.felinediabetes.com/FDMB/viewtopic.php?f=14&t=1122 for information on hypos.
We have what we call Newbie Kits available. If you would like a Newbie Kit, please see here
http://www.felinediabetes.com/FDMB/viewtopic.php?f=14&t=19528.
Have you and the vet discussed what insulin you will be using? If so, can you tell us what it is and what doseage the vet recommended?
You are going to have a million questions...please do post back and we'll do our best to help and support you.