A 10 year old, spayed female Keeshond presented to the Cornell Soft Tissue Surgery service for removal of a large hepatic mass. 4 ½ year history of diabetes mellitus with recent difficulty in regulating was believed to be associated with the hepatic mass. The mass was successfully removed and submitted for histopathology. The mass was diagnosed as hepatocellular carcinoma. After removal of the mass the insulin needed to regulate blood glucose levels decreased. Several theories have been researched about the relationship between hepatocellular carcinoma and blood glucose levels including the production of insulin-growth factor II, disruption of the liver affecting liver function, overproduction of cortisol, and other theories will be discussed in this paper.