Hi Lacy,
I’m not sure where it it you saw corn listed as a high glyvemic food, I see it routinely listed as moderate. Additionally high glycemic foods have not been identified as a cause of diabetes in people( see ADA) and they are not a cause of diabetes in canines. Diabetes is not caused by diet.
Finally, dogs are biologically considered omnivores because of their metabolic pathways align with that classification such as ability to convert B carotene to Vit A which is something the cat, classified as a carnivore, is unable to do.
As Crazy4cas posted corn can be a well utilized component of the canine diet .
