My Kitty Ravan has the same problem, leaking urine. He's 16 yrs old & was diagnosed with diabetes 8 months ago. I've noticed that when his Blood glucose is high he leaks urine more frequently When it comes down to low numbers the dripping nearly stops.
The neuropathy can be helped with B12 Methyl Here's some information
Methylcobalamin Supplementation
Methylcobalamin is a form of vitamin B12 that contains the mineral cobalt. Deficiency of B12 leads to nerve damage, anemia and gastrointestinal problems. The supplement is given in a dosage of one 3 mg tablet, once a day.
Methylcobalamin tablets successfully treat the symptoms of feline diabetic neuropathy in a short period of time. Although neuropathy is cured once the diabetes is regulated,
administration of methylcobalamin supplements aid in faster recovery.
I love that you took him in off the streets! You're a good kitty momma

And he's so Lucky you found him. I've been on the Lantus Forum for 8 months but i don't give dosing advice. It does sound like 2 units of Lantus is too high to start with. A lot of Vets seem to not know how Lantus insulin works & start the Kitties on dose that's too high.
It would be a very good idea to go to the Lantus forum & ask for help. The people there have been donating their help for a long time & they really do know more than most vets about Kitties with diabetes.
Best of Luck to you & Kitty Richard Parker