Part of the endocrine system--the ovaries--which can create high blood glucose situations at each heat cycle until the dog is spayed.
Some conditions and/or medications are the "root" cause of a pet's diabetes. In some cases, correcting the primary problem also corrects the diabetic condition. This is also referred to as transient diabetes because there is a possibility that controlling or clearing up the non-diabetes condition rectifies the diabetes as well.
More Information
See also:Causes