Carolee
I'm glad to see that Kris was here and able to give you some good information on Vetsulin.
This link:
http://www.caninsulin.ca/faq-answers-p.asp
has a lot of information on Vetsulin also called Caninsulin in countries outside of the US. If you read through you will see important points. This link is from the Canadian site but just remember that Caninsulin IS Vetsulin with a different name.
"
How does Caninsulin work in cats?
A lente (intermediate-acting) form of insulin, Caninsulin contains approximately 30 percent amorphous insulin for rapid onset of activity. The remaining approximately 70 percent of the formula is crystalline insulin which is absorbed more slowly. This formulation allows for a more continuous utilization of glucose to support the body's basic functions. In cats, the peak activity following subcutaneous administration of Caninsulin occurs between 1.5 and 8 hours (with an average of about 4 hours), and a duration of activity varies between 8 and 12 hours. Caninsulin should be administered subcutaneously twice a day in diabetic cats."
"In cats,
the initial recommended dose is 1 to 2 IU per injection, and the injections should be given twice-daily (BID) at 12-hour intervals. Initial dosing is based on a per animal basis. The duration of activity of Caninsulin in the cat is between 8 to 12 hours – this is shorter than in the dog. Peak activity level occurs between 1.5 to 8 (average of about 4) hours in the cat."
When first starting any sort of insulin it is suggested to hold the initial dose for 5-7 days..
unless the numbers drop too low...in order for the body to become acclimatized to using external insulin. Dose increases should only be done once adequate data (testing) has been done to see how your kitty is responding to a specific dose. Using a sliding scale with Vetsulin/Caninsulin is a more advanced approach and should only be done once there has been adequate data to show how your kitty responds.
Because Vetsulin has a faster onset time testing in the earlier hours after the shot is a good approach in order to catch any fast or low drops in the glucose levels. When a kitty drops too fast or too much the body produces counter-regulatory hormones which cause stored glucose to be released into the blood stream, since the body "thinks" that this is an emergency situation. When this happens the glucose levels can be elevated for up to 3 days, something referred to as "bouncing" This does not mean that more insulin is required since this will simply cause more bouncing. Recording regular glucose readings over the first week of treatment will show if there are any large ups or downs in the levels and make it easier to determine what dose changes are needed.
Also from your earlier post it appears that you are removing dry food from the diet. Dry food is high in carbs and once it is removed from the diet and out of your kitty's system ( which can take a few days) glucose numbers can drop sometimes quite a bit, depending on the kitty.
The one thing that this forum is always concerned with is keeping any kitty safe.
Please do continue testing and asking for advice. The people on here live and breathe feline diabetes daily and have lots of personal experience and understanding in treating feline diabetes. Not to be unkind, but if your vet gave a starting dose of 5 units, then they do not have a good understanding of how insulin for kitties should be approached. A serious hypo event that is not treated properly can cause neurological damage and even possibly death.