I mostly use strips, but also have a Nova Max meter to test ketones. I was never too convinced on the accuracy of the meter, to tell the truth.
The first time I got a HOT PINK reading - which is MODERATE KETONES - on the test strips, I called the ER vet and the NC State Vet school. Everyone told me to go ASAP. Because he was still eating like the ravenous beast he is, I held off until the morning, and beelined for my regular vet. He got fluids (lactated ringers), was put on an antibiotic, we increased his dose [not sure the protocol on the L's for increasing like that - we were on ProZinc] and we were sent home. I test for ketones VERY frequently, so I caught it early. I continued to give sub-cutaneous fluids (SubQs or Squids) for several months... initially 2x/day, then 1/day, then every other day. He got MOD KETONES two more times, and again I upped the fluids and dose. He's not had them since.
The vet school told me it generally costs $2-4000 to treat him if he goes DKA. Usually, however, by the time they see the pet, they haven't eaten for 3 days. This is why I was able to hold on until the morning... but otherwise, I would've at least gone to the ER vet.
My posts at this time were on PZI about Feb 23rd or 26th. feel free to take a look if you think it would help. Test strips (bottle of 50 for about $6-10) is the cheapest/best form of insurance you can get against ketones. Good luck. Let me know if I can offer anythign further.
Lu-Ann