Hometesting supplies are not expensive - about $40 for everything so less than a vet visit with testing. Here is a shopping list:
A human glucometer. Any one that sips and takes a tiny sample is fine. Some members stay away from any meter with True in the name and the Freestyle meters. Some people think they are unreliable and read lower than other meters. The meters are often free at drug stores; it’s the strips that are expensive. You can, however, buy them on ebay at less than half the price of stores. Lots of people here also like the ReliOn from Walmart. It is an inexpensive meter and its strips are the cheapest around. Try the meter out on yourself or someone else before you try it on your cat. You want to be familiar with it before you poke the cat.
Lancets and a lancet device. Usually, until the ears “learn” to bleed, a 26-28 gauge is good. Any brand will work as long as the lancets match your device.
Ketone strips. (Ketostix) Just like human diabetics use. You will sometimes need to test urine if the numbers are high.
Rice sack. Make this out of thinnish sock, filled with raw rice or oatmeal and then knotted. You heat this in the microwave until very warm but not hot. Then heat the ears before poking. You can also use a prescription bottle filled with very warm water. It provides a good surface to poke against.
Also nice to have. Flashlight: so you can look at the ears and find the little capillaries that come off the vein running down the ear. Vaseline: Put a tiny smear where you want to poke. It will help the blood bead up.
And some lo carb treats to give your kitty, successful test or not
Lo carb treats
To get Kedo ready, first pick a place where you want to test. Some people use the kitchen counter, a blanket on the floor, between your legs while sitting – whatever works for you. Take the kitty there and give him lots of praise while you play with his/her ears. Give a treat and release. Next time, add the rice sack (thin sock filled with raw rice, heated in the microwave until very warm but not hot) or a prescription pill bottle filled with very warm water. Lots of praise, treat and release. Finally add the lancet so he will get used to the noise. The hope is that when you finally poke, they will be used to the process and know a treat is coming!
Hills WD is 37% carbs. We try to feed 8-10% carbs. Feeding a high carb dry food to a diabetic cat is a little like a human diabetic regularly eating donuts and then taking additional insulin to counter the bad diet. You might be surprised to see how much better his numbers are on low carb. The website I gave you has great transitioning ideas for getting even hard core dry fans to change to wet. There are lower carb dry foods if he absolutely won't eat wet.
At this point, if he were mine, I would try hometesting and another food before thinking about another insulin. I have been helping ProZinc/PZI users for many years on this site and have seen little difference between the two forms of PZI. If diet and testing doesn't help (which I am convinced it would) then you might try another insulin completely.