The Hill's Prescription Diet Glucose Management dry food, also known as Hill's W/d, is really high in carbs, around 37%. It's what the cat shelter and vets had my diabetic cat Wink eating before I took him in as a foster. Unfortunately, that W/d dry was keeping him at unregulated blood glucose levels. Once I switched Wink from the high carb dry to wet food, he quickly went OTJ (off-the-juice, insulin being the juice).
I know your food choices are more limited since you live in the Virgin Islands. I think BJM's idea to make your own food might meet your needs very well.
p.s. Would you please consider putting some information in your User Control Panel for us? It would be really helpful if you would update your information so we have your location, and a bit of information in your signature such as your name, cat's name, diagnosis date, insulin used, meter used for testing, any pertinent health information for your cat on other health issues, etc. Thanks for considering this request.