Justin is a 6.5 year old, male neutered, domestic short hair cat. He has been generally healthy. Over the past couple of months he has been drinking and urinating more. He has also seemed to lose weight. He used to be about 19 lbs but is 14.5 lbs today. There has not been any vomiting. He is always hungry and seems otherwise normal. On physical examination his vital signs are normal. He is bright, alert and responsive with an obese body condition score at 8/9. He has moderate tartar but appears to be generally otherwise normal on physical examination. Labs showed a mild increase in 1 liver value and blood glucose at 447 mg/dl. Urinalysis showed a large amount of glucose, small amount of ketones and a large amount of blood. Even though bacteria was not seen in the urine, a culture was submitted. This returned with no growth several days later.
What is your diagnosis and treatment?
Justin has diabetes mellitus. Treatment is insulin therapy, dietary therapy and weight loss.
Blood sugar (glucose) is absorbed by the intestines from food and produced by the liver. A complex process tightly regulates glucose levels primarily by 2 hormones produced in the pancreas, insulin and glucagon. Insulin is required to move glucose into most cells in the body. Without insulin, these cells cannot transport the glucose and must find an alternate energy source. The cells still want glucose and signal this to the pancreas. The result is increased glucose production and levels in the body.
In the kidneys, the glucose normally passes into the urine and is then completely reabsorbed. The kidneys are limited in how much glucose they are able to reabsorb, so with diabetes glucose leaves the body in the urine. This can add up to be a large number of calories and cause weight loss. Additionally, glucose is hygroscopic, it readily absorbs water. Therefore, water follows the glucose out in the urine thereby producing more urine. The patient drinks more water to maintain hydration due to urinary losses.
Cats usually develop Type II diabetes. This is the same as most adult humans who develop diabetes. In both cases patients are usually overweight and not very active. The body's cells develop a resistance to the insulin. Initially the pancreas can make enough insulin to compensate and provide enough to allow glucose into the cells. But as time goes on, the cells that make the insulin seem to burn out. The insulin must then be supplemented.
In contrast, dogs usually get Type I diabetes. This is the same as what is referred to in humans as juvenile onset diabetes. It is an absolute lack of insulin production by the pancreas. In dogs it is an autoimmune disease, the immune system attacks normal cells in the body.
Justin has a fairly typical presentation for diabetes mellitus. Cats usually drink and urinate excessively. Despite a healthy to voracious appetite, they lose weight. They generally act fairly normal but the hair coat often suffers, likely from nutritional stress. There may be some occasional vomiting and increased stool production due to the increase in appetite.
Justin is lucky in some ways, he is still acting healthy. He is what we refer to as an uncomplicated diabetic. Some diabetics become severely, life threateningly ill. This would be referred to as a complicated diabetic or diabetic ketoacidosis. As Justin is still relatively healthy, he does not require hospitalization. We can just start him on insulin therapy.
Justin is currently responding well to insulin therapy. We are still working on getting him regulated. We started him on a calculated dose of insulin twice daily. We have kept him for the day a couple of times to check blood sugar levels over the course of the day (what we call a glucose curve). His thirst and urination have improved but we have not quite got his blood sugar levels where we want them, although we are getting closer.
Each diabetic patient is an individual and treatment must be tailored to the individual. This can take some time. After each adjustment of insulin dose, we wait about a week to check a curve to see what adjustments need to be made. Treatment is expected to be lifelong. Diabetes is a disease of chronic management, not something that we ever expect to cure. Although, some cats do seem to go into remission.