Yes, diabetes is common in older cats, and is caused by the high carb dry foods we tend to feed them their whole lives. Dry food can also contribute to kidney problems. Both of these diseases have symptoms in common.
I know I've written some stuff about this in the past. Let me see what I can dig up instead of writing it all over again.
Well here's one, but this person already had a cat diagnosed with diabetes, so note that my post is directed at what she said, but it still applies if that's what your cat has.
http://www.askmehelpdesk.com/cats/ca...ar-218804.html
Well, I can't find the other one, so I guess I'll have to repeat some of it.
Really, the best way to determine what is going on is the vet's, sorry. Everyone is always looking for a solution to something that requires a vet, without the vet. You really can't diagnose kidney problems without blood work. And for diabetes, it sure helps. However, I can give you one suggestion, which is to get glucose test strips at the pharmacy, if you can afford that. They don't require a prescription. When the glucose level gets up to approximately 250 they start spilling it into their urine, so if glucose is showing up in their urine they are more than likely diabetic. And that test you can do at home. However, it's a good idea to get a confirmation with blood testing.
If you read the above link, I talked about blood glucose testing at home. If I were near you, I could actually come over and test your cat myself for glucose level. (Can't do a blood workup, no, but I can test just blood glucose.) If I knew where you were, I might know someone near enough that could come do this. That would actually only confirm high glucose levels, because certain diseases and stress can make their glucose go whacky too. If it's
really high, it's probably diabetes though. (You can PM me and let me know where you are so I can check if you like.)
And there are other things that cause weight loss. It would be nice to have an answer to the question about the drinking and urinating a lot, and also any other clinical symptoms, such as appetite problems, vomiting, constipation, scruffy fur, anything that seems different or unusual to you. With diabetes, usually what happens is eating a TON but still losing weight anyway - that's a classic symptom. If it's just the weight loss, that could be other stuff.
And this stuff does need to be treated. There are some things you can only treat to an extent. Other things (like diabetes) can be totally controlled and would not prevent the cat to continue to live a full life. I know of some resources and you might even be able to get certain supplies and stuff from other people, but you still need to get into a vet to find out what is going on.
Let us hear back what other symptoms might be going on and see if we can figure out where you can go from there.