Diabetic Kitty?

We have a cash pay program here at work for a free new glucose meter and the strips are $19.95 for 50.  Cash pay doesn't go through insurance or need a script from the doctor, just a credit card on file.  I talked to a lady today to verify a cash pay and how often to send the strips.  She had already given us her credit card, I was just verifying how many strips to send and how often.  And I found out its for her cat.  She made it very clear that the meter and strips are for her cat, not her.  I didn't know people tested their pets blood sugar levels.  And my next question is how do you test a cats blood sugar?  And how do you find out your cat is diabetic?