Hiya Becky,
Which Felix are you feeding? Is it the 'as good as it looks' version? If so this is not ideal because in
some cats it can elevate the blood glucose
enormously. I think this is because of the 'vegetable protein extract' it contains. Not all cats are affected in this way. My diabetic cat is one of those that is affected and the only reason I keep this in the house is in case of dire emergency - ie, if Bert's blood glucose drops too low. There are a few other foods on the market that also contain 'vegetable protein extract'.
However, if you are feeding a food that contains this ingredient I would only advise changing the food
if you are testing Winston's blood glucose at home. This is because Winston's blood glucose level may drop if you switch foods, and if you're not 'hometesting' you won't be able to ascertain if this is the case. If his blood glucose does drop then his current dose of insulin could be
too much...
Are you testing Winston's blood glucose at home? If you are then you could monitor during the food switch to see if there are any changes in his blood glucose, and reduce the insulin dose if necessary.
For a diabetic cat it is recommended that the food has less than 10% of calories from carbohydrates.
As Deb said above, another UK member, Juliet, has just put together a spreadsheet listing cat food varieties, their approximate carb values, and where they are obtainable from. There is a very wide range of foods available now. Many of these are not available from supermarkets though and need to be bought online. The link to Juliet's post (giving link to her spreadsheet) is here:
viewtopic.php?f=28&t=64843#p1059149
Current popular brands
include (listing from cheapest to most expensive); Butcher's Classic (available from supermarkets); Bozita (available online from Zooplus, and also at some independent pet stores); Macs, Ropocat and Granatapet (available online from The Happy Kitty Company); Catz Fine Foods and Grau 'grain free' (available from Zooplus); and Lily's kitchen (available online and in some supermarkets).
What you choose to feed will depend on your budget, how many cats you have, and what they will agree to eat! ;-)
Is there a particular reason why you want to change the food?
How is Winston getting on?
Eliz