I am still checking out your question but want to paste this info here first which doesn't answer your question about the diabetes but it is a start. Question for you--Why do you want to give cranberries? Urinary tract infection? Or what?
Can I give my dog cranberry juice? NO Cranberry juice is a popular and effective home remedy for the treatment of urinary tract infections when taken along with a prescription antibiotic. A chemical in the cranberry prevents bacteria from adhering to the wall of the bladder. While drinking cranberry juice is a good choice for humans, dogs should not drink cranberry juice. However, dogs may be given small amounts of cranberries; large amounts can cause diarrhea, and increase bleeding time. If you suspect that your dog has a urinary tract infection, it is important that the underlying cause is identified and that your pet receives the appropriate antibiotic from your veterinarian. Always consult with your veterinarian before giving your dog any natural or herbal products. The link for this info is:The most frequently asked "Can I give my dog this" questions.That info is off the net.
I found this too which may be of interest--about diabetes, not cranberries!
http://www.articlesgarage.com/natura...iabetic-dog-2/
Also found this but I don't know how much carbohydrates/sugar would be in a capsule!! I would certainly find out before giving to your diabetic dog!!
Canine & Pet Diabetes presents Dr. Jennifer Fry
This link is about diabetic humans and cranberries. Now this may be different for dogs!! FOR SURE--NEVER GIVE ANYTHING WITH ARTIFICIAL SWEETENERS--HARMFUL/CAN BE DEADLY!! --->
Cranberries for Diabetes: Can They Lower Blood Sugar
Came across this for the amount of carbs/sugar in cranberries:
Cranberries have been making a lot of health news recently – it seems they are good for almost everything! This is great for low carbers, because they pack a lot of nutrition, fiber, and flavor into a package without many carbohydrates. Half a cup of whole cranberries has 4 grams of effective carbohydrate, plus 2 grams of fiber, 1/3 of which is soluble (the soluble fiber is what makes the “gel” when you cook cranberries).
That is about all I can find! My 'take' on your question is that cranberries (natural--not dried or sugar added--just plain berries--Could crush and add to the food. If your dog likes cinnamon--could crush and add a little cinnamon and then add to dog food.--Cranberries should be good for diabetes--just don't overdo and take note of all links I have listed!! Do not add any other spice --esp. nutmeg as is hazardous to a dog!! Here is another good read for you: Foods that are hazardous to a dog