I have been giving our lovely senior citizen cat, Squish, Solensia for 3 months - he is 22, and also a diabetic since he was 17.
For the last two or three years Squish has had a very rough time walking up the stairs, not jumping as much and generally not being very active. Our first vet thought he had diabetic neuropathy, but his diabetes has always been in check and treated accordingly. They mentioned arthritis but never really investigated. Due to moving we changed vets and when they saw him said he had very little muscle mass in his back legs and lots of arthritic lumps. In fairness his mobility was getting really bad by this point. Previous vets recommended Metacam every three months, but it was making him better for a week or two and then he would go back to not really doing much but sleeping and walking round the house a bit. They recommended Solensia as it hadn't been out on the market for very long, and at his age it wouldn't hurt if it gave him more mobility.
It has been a miracle drug for Squish! He can go up the stairs, jump on his little footstool (again!!), and generally walk about more and climb onto things. He was unable to even go up a step without falling before. He is a trooper and most people think he's about 17 and certainly not 22! It took about 3 weeks to start seeing the first effects, and it was small changes. He became less wobbly, and started go up small ledges and steps so we knew it was working.
It's quite pricey, and for me with the diabetic treatment and regular flea/working food etc. It adds up to quite a lot, but his happiness is priceless so I would pay as much as possible to give him as many good years as I can. I'm so happy about this drug and I can't rave about it enough!! I know it only works on about 68% of cats, but it's worth trying. :)