Diabetes Mellitis

What is Diabetes Mellitus?

Diabetes mellitus is dysregulation of the body’s metabolism of sugar (in particular, a sugar known as glucose). Glucose comes from the diet in the form of starches and sugars that our pets eat. Tissues cannot absorb glucose unless a hormone known as insulin is present. Insulin is produced by the pancreas as part of the body's natural blood sugar regulation. Insulin allows the sugar in the bloodstream to enter the cells of the body to be used as fuel. Without insulin, the sugar stays in the bloodstream and cannot be used by the body. In the diabetic animal, there either isn’t enough insulin produced by the pancreas or the body is not responsive to the insulin. 

What are the symptoms?

The main signs of diabetes are excessive thirst and urination, increased appetite and weight loss. Since the body is unable to use any of the glucose in the bloodstream, the body breaks down fat and muscle for energy. Diabetics are excessively hungry because the body is starving and unable to obtain energy.  Because the body is breaking itself down, diabetics also experience weight loss. All the sugar collecting in the urine serves as an hospitable environment for bacteria and therefore urinary tract infections are common. The glucose in the bloodstream is also able to enter the lens  and pull fluid in, leading to cataracts in dogs and eventually blindness.  The development of cataracts occurs in all diabetic dogs. 

How is Diabetes Mellitus diagnosed?

Diabetes is diagnosed by blood and urine testing.  High levels of sugar in the blood and urine indicate that a patient is diabetic.  

How is it treated?

It is important to note that in dogs, diabetes is permanent, while in cats it may not be.  Similar to humans with diabetes, the treatment involves insulin injections. Insulin type and dose is patient and species dependant. It is impossible to know exactly how much insulin an individual pet will require. Often a patient is started at the low end of the dosing range and adjustments are made weekly to monthly depending on the patient. Most pets require insulin injections twice a day, following a meal.  Insulin is generally administered subcutaneously using a syringe. Each patient receives a prescription for a bottle of insulin and a box of syringes. A measured amount is drawn up from the bottle of insulin and administered in a “pocket” under the skin.  It is always important to make sure the insulin syringes and insulin concentration match. Insulin syringes are marked in insulin units (either “U-100” syringes for 100 unit/cc insulins or “U-40” syringes for 40 unit/cc insulins. *For more information and videos on how to give injections visit www.vetsulin.com 

Diet and Feeding

There are special prescription diets recommended for veterinary patients with diabetes to make blood sugar fluctuations more manageable. For dogs, a higher fiber diet is generally recommended (including DM, glycobalance, W/D). High fiber diets slow absorption of sugars and help maintain more regulated blood sugar levels. It is recommended to feed diabetic dogs in two meals, every 12 hours and to have a dog eat at least 50% of its meal before administering insulin. Cats generally require lower carbohydrate diets. Cats often become insulin resistent secondary to being obese, therefore weight loss is often also recommened in diabetic cats. The diets available for cats include DM, M/D, W/D and glycobalance. 

Glucose Testing

In order to determine how a patient is tolerating insulin and if the dose needs to be adjusted, glucose measurements are required. Glucose measurements can be obtained in the clinic (usually approximately 4-6 hours after administration of insulin, as this is likely to be the time of the lowest blood sugar in your pet) or at home. At home measurements tend to be more accurate as pets are much more relaxed. For at home measurements you can purchase an alphatrak glucose monitor. This is the most accurate monitor in our pets. You can obtain a blood sample from the ear or the paw pad (videos available on the vetsulin webpage). Depending on the patient a one time “spot” blood sugar will be recommended or a full blood glucose curve (checking blood sugars every 2-4 hours after insulin administration) for a full 12 hours. There is also a device called the Freestyle Libre. This is a continuous glucose monitoring system for humans, now being used in our pets. 

The freestyle libre - This system allows pet owners to monitor blood sugar without any blood collection or pokes. Flash glucose monitoring systems measure the glucose in the fluid that is present in the tissues under the skin (interstitial fluid glucose). A sensor is placed in your dog or cats subcutaneous tissue that can continuously measure blood sugar for 10 days. The sensor is purchased at a human pharmacy with a prescription from your veterinarian. You will also need to purchase a reader or use the Iphone app to scan the sensor at least every 8 hours. The data can easily be emailed to a veterinarian. 

Fructosamine levels - This is a blood test performed at a veterinary hospital also used for monitoring. Measuring fructosamine in the blood gives a sense of the average blood sugar over the past couple of weeks. Fructosamine is a metabolic marker that accumulates and lasts for 1-2 weeks. Control is designated as “excellent,” “good,” “fair,” “poor” or “prolonged hypoglycemia.”   

Urine Testing

Another form of monitoring our diabetic patients is testing the urine for glucose and ketones. Ketones are a by-product of intense fat burning. Excessive ketone production can be very dangerous and can lead to pH changes and dangerous electrolyte abnormalities. When diabetes is complicated by infection or other problems, ketones build up and make our pets feel very sick. For our diabetic patients we expect there to be sugar in the urine (due to excessive sugar in the blood) and no ketones to indicate good regulation. Keto-diastix are urine sticks that can be purchased over the counter at any pharmacy or online. Urine is obtained from your pet and applied to the squares on the dipstick. A color guide is present for monitoring. Ideally there is trace to 1+ sugar in the urine and no ketones.  If there are ketones in the urine, please contact us.  

This testing is much easier in dogs but can be done in cats by placing only a small amount of litter in the box( so all the urine isn't absorbed), using unpopped popcorn or special non-absorbent litter from your vet. 

*Please follow the guidance of a veterinarian to determine how often urine testing is recommended for your pet. 


One of the most serious and common complications to look out for in diabetic patients is hypoglycemia or low blood sugar. This results from a mismatch in food consumption (providing glucose) and insulin dose (promoting removal of glucose from the blood and into the tissues). If a pet doesn't eat or the insulin dose is too high (or administered twice), hypoglycemia can result.  The most common clinical signs are lethargy, weakness, a drunken or wobbly gait or decreased awareness. In more extreme cases of hypoglycemia seizures can result. If your pet appears lethargic, wobbly or dazed your pet's blood sugar may be too low and this can be an emergency. It is recommended all diabetic pet parents purchase Karo Syrup over the counter at any local food store to have on hand if needed. If you are concerned about hypoglycemia, first try and feed your pet if he/she is alert, then administer Light Karo Syrup, honey or sugar water at 1 tablespoon per 5 pounds and call your veterinarian.  Karo or honey can be applied directly to the gums. If you know your pet has experienced an overdose please call your veterinarian or a local emergency veterinarian overnight.

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