What medical problem?

I'm going to put a disclaimer in here up front, before someone goes on about it. I know you guys aren't vets or vet techs, and only a vet is qualified to actually diagnose. However, some opinions would be nice :)

So, I'm dog sitting this dog for my friend, and have been dog-sitting him for almost two weeks now. I've noticed some weird things about him. He is a 7/8 month old chocolate lab. He drinks excessively, and pees excessively, and although he's being fed enough, and of high quality food (orijen), he's often looks for extra. However, that could be due to him having been fed scraps from the table by his owner.

Anyway, on to the symptoms. He drinks, a lot. I can fill his dog water bowl (and it's a big one), 3 times a day. Except at night, he's peeing at least every 3 hours, and often every hour (I've timed it). And then he just gulps water down again. Now, from what I've read, this is indicative of diabetes. However, I've also noticed that....basically, what he eats, he poops. His poop is pretty much the size of what he's fed - I would think it should be less - that he'd extract more of the nutrients out of it. And take a bit longer to digest, because he's pooping within 1-3 hours of eating (usually closer to 1). Another example of this, is, I gave him a chewable/eatable *bone* (not an actual bone, but is a chewy made to look like one) an hour ago, and he just now, told me that he Had to go potty, and pooped out poop the size of the bone, and a different colour than his normal poop. So....things go through him like a sieve.

Is this still indicative of diabetes? Anyone know what else it could be indicative of?

Any suggestions and opinions would be welcome. And yes, I'm going to try and persuade the owner to get him to the vet and checked out.