Glad he was okay today while you were gone. On days that he starts off with a lower number, you might want to try to come home for a test those days since you said your lunch time is flexible.
To help get the numbers down, ditch that brand dry food. Young Again (less than 1 % ) and Dr. Elsy's are better choices for dry as far as dry foods go , but it is much better if they are eating wet lower carb food. If you get him off the dry, you can follow TR protocol and get him into lower numbers faster. As long as dry is in the picture, you should follow Start Low Go Slow ( SLGS) method as it is safer for kitties eating dry as the dry takes longer to clear their system and the dose increases are done at a slower pace.
You can leave canned food for him through the day. Someone all ready mentioned getting an auto feeder and having timed feedings for him and some peeps will freeze the portion the night before and put it into the feeder frozen so by the time the slot spins open his food would be thawed. Or you can do the same leaving it on a plate for him.
He'll get there, but making sure his food is all low carb ( under 10% ) will help too. It is amazing how much a carb load will boast the numbers up.