There are different types of insulins being used and different types of syringes. Some people, like me, are using a U-100 insulin (like Levemir or Lantus), so there is no conversion involved. If we want to give 2.75, we pull a dose that falls mid-way between the 2.50 and 3.00 marks on a U-100 syringe. We have to 'eye' the dose, there is not actually a mark there. Likewise, some people are using U-40 syringes with their U-40 insulin (like Prozinc or Vetsulin), so there is no conversion involved there either. They just pull a dose that falls between the 2.50 and 3.00 marks on the U-40 syringe.
Since you are using U-40 insulin but U-100 syringes, there is conversion involved. You have to multiply the U-40 units you need to give times 2.5 to know what mark to use on the U-100 syringe... or just use the conversion chart to avoid any confusion or mistakes. If you follow the chart you will go from 2.6 to 2.8 and not worry about 2.75. If you were to find that you needed a dose between the two, you would probably want to 'eye' a dose between the 6.5 and 7 unit marks which would be 6.75 units which equals 2.7 units of U-40 insulin.
When someone is having to make dosing changes in very small increments, you may see things like an 's' for skinny or an 'f' for fat next to the units.. skinny means just very barely less than and fat means just very barely more than. If it says 'a drop' that means they literally gave just a drop of insulin. When a cat is going into remission and being weaned off of insulin, the dosing sometimes goes down that low before it stops.
Don't let all of this confuse you. Just keep using the chart. It allows you to change dosing in increments of .2 which should be just fine. Should there come a point where you have to do anything other than what is on the chart, just reach out for help here.
