What is diabetes mellitus?
Diabetes mellitus (DM) is relatively common in both cats and dogs. It is caused by a lack of the hormone, insulin, which is required to draw glucose into cells. Glucose is a vital source of energy for the body. When animals don't have enough insulin, glucose stays in their blood stream instead of going into cells. With glucose staying in the bloodstream instead of going into cells, cells are deprived of glucose as an energy source. This energy deficiency makes diabetic animals become weak and they may also eat more.
What causes diabetes mellitus?
Sometimes it can occur spontaneously, often for no obvious reason. However there are certain risk factors that can increase the likelihood or incidence.
- Obesity - fat animals are far more likely to develop spontaneous DM
- Age - older animals are more likely to develop DM
- Pancreatic injury - often DM can develop after pancreatitis or due to pancreatic tumours
- Drugs - certain drugs (corticosteriods, some hormones) can trigger DM
- Breed - Burmese cats are particularly predisposed to developing DM
What are the clinical signs of diabetes mellitus?
There are a variety of signs and each animal may vary slightly. However usually affected animals show one or more of the following:
- Excessive thirst
- Increased frequency and volume of urination
- Increased appetite
- Weight loss
- Urinary tract infections
- Rapid onset cataract formation
How is it diagnosed?
DM can be diagnosed in a variety of ways. The presence of glucose in the urine is highly suggestive, but not absolutely diagnostic of DM. In order to positively diagnose DM, the animal must show increased blood glucose, glucose in the urine and clinical signs consistent with diabetes. Blood glucose and urine tests can be performed in seconds at the clinic.
Treatment and monitoring
The mainstay of treatment of DM is giving regular insulin injections. The dose required to control each animal can vary enormously and so the initial stabilization phase can be quite time consuming and involved while the correct regime is established.
Ideally we perform a glucose curve when we start insulin treatment. A glucose curve plots the blood glucose levels throughout the day, following an insulin injection and eating. This involves having the animal at the surgery for a day and we start them on a calculated dose of insulin, and then measure their blood glucose every 2 hours to observe the response. Using this information, we can then either increase or decrease the amount of insulin being given. This is almost always done in dogs, but is not so useful in cats, as their blood glucose can be more erratic with stress. With cats it is sometimes easier to measure their fructosamine levels after a few weeks and then adjust the dose accordingly.
Ideally we want the levels to stay within the “normal” region and neither dipping too low, nor returning too high before the next insulin treatment. On the basis of this curve, we can decide if your pet will need more or less units of insulin per day.
Diabetes can be a serious condition but with close monitoring and communication between you and your vet, your diabetic pet can lead a happy and healthy life.