Insulin & Blood Glucose Reading Question?

My vet put my cat on 2 units of Lantus twice daily. I just got his glucometer in the mail yesterday. So yesterday I checked his bgc reading at 10am even though he had gotten his insulin at 7am. I just wanted to see what the numbers were. Well they were 353mg so then later on in the night I fed him at 6:30 pm, gave him his insulin at 7pm and then tested his bgc at 8:40 pm and it was 122. All of this sounds great. Well today I started his first curve test so I fed him at 6:30pm then tested his bgc before his injection and the numbers came out to 82 and I was thinking that can't possibly be right so I tested again and got 117. I'm using an AlphaTrak II as well so it's just for animals and I have it set for cats. Anyway, my main worry now is that with a reading of 117, should I withhold his insulin injection for now or give it to him anyway? I'm scared that it will bring his bgc down way too far. I'll be testing his bgc in 2 hours so I could give it then if the numbers are high. How should I go about this?