I'm assuming that your dog's bloodwork has included a test for diabetes, but you should double-check this with your vet just to be sure.
What it sounds more like is spay incontinence
. This is when a valve in the urethra of older spayed females does not close properly and they will leak urine every time they lay down (which puts pressure on the bladder). The open valve also allows bacteria to enter, causing frequent UTIs.
Now given that she is 14 it could be plain old loss of bladder control. But if you've noticed the trend is that it happens when she's laying down then I'm willing to bet it is spay incontinence. This is easily remedied by a tiny hormone pill given about once a week. Less than $1 a pill. Talk to your vet
Chase (Friendly Resident Wigglebum) - Border Collie/Lab/Shepherd X
Kailey (Misunderstood Gentle Beauty) - GSD & foster failure #1
Rupert (Gold-Medal Winner of the 3 a.m. Kitty Destruction Olympics
Heidi - RIP my sweet baby girl