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That is a huge cutback in insulin without testing.
Inappropriate urination very likely could be attributed to poorly regulated diabetes. In addition, diabetes is well known to predispose to other problems includng urinary tract infections.
Also, I believe you meant to say he was showing signs of hypoglycemia, and that's why you cut back.
But, that was a huge change in insulin dosing with no testing of blood sugar prior to the change.
Definitely, get him in to a vet for blood sugar measurement and a urine test.
No, I don't necessarily believe he is dying, but I definitely suspect his diabetes currently is not well controlled.
Hope that information helps.
Hope everything is going okay?