Diabetes, a common condition for humans, is also relatively common in domestic animals like dogs. Type I diabetes is the more severe form of the disease, as it is dependent on daily insulin injections for maintaining blood sugar balance (insulin dependent diabetes mellitus – IDDM).
An affected dog will be hungry a lot of the time, since glucose is not making it to the brain; glucose levels in the brain are too low for the brain to register that it is receiving food. Because insulin is not giving the muscles and organs the signal to convert glucose to energy, the excess glucose in the blood will be carried out of the body in urine instead of being used for energy, and there will be a concurrent lack of energy. There is also increased thirst as a result of the increase in urine. The liver is adversely affected by this condition, as are the eyes and kidneys.
To read more and watch a great video from petMD, go to: http://www.petmd.com/dog/conditions/endocrine/c_dg_diabetes_mellitus_wo_complication