What is Diabetes Mellitus in Dogs and How Do I Manage It?

Diabetes mellitus (often called simply diabetes) is a disorder in which the level of sugar in the blood is too high. In dogs, it is usually caused by a deficiency of the hormone insulin. During digestion, carbohydrates are broken down into glucose (a simple sugar), which is absorbed into the bloodstream. Once in the bloodstream, glucose must enter the body’s cells in order to be used for energy. Insulin signals the body’s cells to absorb glucose from the blood.

A lack of insulin creates two dangerous conditions. First, the body’s cells cannot absorb glucose without insulin; they begin to starve despite the abundant glucose. Second, because the body’s cells do not absorb glucose, the blood glucose level remains dangerously high. With its cells starving for energy, the body begins to break down its protein, stored starches, and fat. As muscle is broken down and carbohydrate stores are used up, weakness and weight loss occur. As fat is broken down, substances called ketones are released into the bloodstream where they can eventually cause diabetic ketoacidosis, a severe complication of unregulated diabetes.

Meanwhile, the excess glucose circulating in the bloodstream can have harmful effects as well, including development of cataracts, pancreatitis, and skin and urinary tract infections. The excess glucose is eventually excreted from the body through the kidneys. As the glucose passes through the kidneys into the urine, it pulls water with it by diffusion. This causes increased urination, which leads to increased thirst. Diabetes often develops gradually, and owners may not notice the signs during the initial stage of the disease. Common signs include increased thirst and urination, increased appetite, and weight loss. Diabetic animals often develop chronic or recurrent infections.

Dogs with poorly controlled diabetes often develop cataracts, which commonly leads to blindness. A diagnosis of diabetes mellitus is based on finding high levels of sugar in the blood and urine.

To successfully manage diabetes, you must understand the disease and take daily care of your pet. Treatment involves a combination of weight loss (if obese), diet, and insulin injections generally twice daily. Usually after being diagnosed with diabetes, dogs are hospitalized for a day or two, and multiple blood samples are taken to measure the blood sugar level throughout the day. This information is used to determine the amount and timing of your pet’s meals and the dosage and timing of insulin injections. After this initial stabilization, your veterinarian will provide appropriate instructions on managing this regimen at home. Periodic reevaluation is necessary to ensure that the disease is being controlled. Based on these reevaluations, you may have to change your pet’s treatment regimen over time.