I've been testing him from time to time, and getting blood work done at the vet every six months, and his A1C, fructosamine, and blood sugar levels are absolutely normal. (Well, not the glucose levels at the vet, he's very stressed there and they shoot up, but they come back down after he gets back home, I can watch them go back to normal over the next few hours if I sample his ears). The vet does the physical exam then when we talk after the results come back keeps looking at his blood work and saying, "this all looks perfectly normal" as if he doesn't believe what he's seeing. Thyroid normal, kidney function normal, liver function normal, long-term blood sugar levels normal, short-term levels normal (per my testing). The only real issue is that Tux is starting to become a bit frail, but the vet is like, "he's 17 years old. Is he eating? Drinking? Is he urinating and defecating? Old cats are like old people, they tend to get frail over time." Yes, he's definitely eating / drinking / etc., I guess he's just old. He's still getting around fine and seems content, so. Current diet -- mostly Fancy Feast Kitten Turkey Feast, I decided he needs the extra calories from fat, and besides, it's good for the kitten (who showed up on my patio one day last fall with his two siblings and I ended up adopting two of them out but he stayed). Occasionally Dr. Elsey's Clean Protein. They're eating roughly four cans of the FF per day, the Clean Protein is for if I'm not around to put out food (overnight trip or etc., I have an automatic cat feeder that drops a measured amount four times per day). I have three litter boxes and three water bowls for the two cats, but they eat together just fine. Tux is napping on his cat chair by my office chair right now and accepting occasional ear scritches as are his due.