Diabetes in dogs is very hard to manage, although easier in males than females, because of the hormone rush caused by seasons. I had to have my Katy spayed as an emergency when she started to come into season. Katy was 9 when she developed it.
Sugar cataracts are almost invariable because as dogs cant tell us when the start to go hypoglycaemic we have to err on the safe side. (Humans can feel it coming on and eat a sweet biscuit or the like.) The cataract surgery is not as straight forward for dogs, and the operation was perfected by Prof. Peter Bedford. But it was too late for Katy. At the time when he was working on the procedure my friend and myself held a number of dog shows to raise money to buy a phacoemulsifier, (The machine used to break up the cataract.) Peter is a very clever man and although now retired from the RVC he is still the head panellist on canine eye health testing. (I was actually with him last Thursday.)
If you now have the sugar level stabilised the muscle tone should soon start to improve. Consistency in everything is the key. I never changed her food so her sugar intake was always the same. I also fed her 3 times a day to try to spread the sugar intake throughout the day rather than peak loading. I even controlled her exercise so the burning off of the sugar was constant.
I took a urine sample every day, and using clinitest tablets checked the sugar level with dipslides, then injected her accordingly. (Are you doing the same thing, or have things moved on since Katy died over 30 years ago?)
But Diabetes is very debilitating and affects various other parts of the body. With Katy her circulation deuterated until I finally lost her at about 13.5 years old.