Good vet!! We do support hometesting here, so it's great to see that you have a vet of the same mindset. It really isthe best way you have to care for your cat's diabetes; it allows you to monitor the BGs at home, watch for hypo episodes, and know if it is safe to shoot. It's not that scary, and we can walk you through it. Many, many pharmacies will give you a free meter with purchase of strips. Ask for one that uses the smallest drop of blood- your cat will thank you! (And there's no real need to tell the pharmacy people that it's for your cat. ;-) )
The excessive urination and drinking (PU/PD) and weight loss are clear indicators of non-regulation, so hopefully you will see a turn around in that very soon.
While you are at the pharmacy, please get a bottle of ketostix, as well, to monitor the urine daily for ketones.
I am a little concerned that you are already up to 2u of Lantus ... without hometesting, it's hard to tell if you have overshot the optimal dose (sorry- no pun intended). Pop over to the Lantus ISG and take a few minutes to read their sticky notes - very valuable info there :
viewforum.php?f=9
Now we need to know about diet. As with humans, diet is very important in controlling feline diabetes. Can you tell us what you feed Jack?
Most important ... welcome aboard! There's lots to learn, so take your time and absorb. You're in a good place, and we're here to help.