Diabete mellitus

Diabetes mellitus represents one of the most common endocrine disease of dogs and cats.

Many owners of diabetic animals find it difficult to understand the disease and in its therapeutic management. Diabetes is commonly considered a frustrating disease, often with poor chances. In order to better understand the disease and help owners of diabetic animals, this web-page contains the most frequently asked questions. Every question is followed by a brief answer. If the reader wishes to receive more details, Dr. Eric Zini, responsible of the Internal Medicine department, can be contacted at the following email address: 
eric.zini@anicura.it

What is diabetes mellitus? 
Diabetes is a disorder of carbohydrates metabolism, due to an absolute or relative insulin deficiency. Diabetic dogs and cats cannot keep their blood glucose concentration within normal limits; thus, glucose increases (hyperglycemia). 

What is insulin? 
Insulin is a hormone produced by beta-cells in the pancreas. The principal function of insulin is to maintain the concentration of glucose in the blood within normal limits and to convert the excess energy into fat (reservoir). The target organs of insulin are skeletal muscles, fat tissue and liver. 

How is diabetes classified and what are the causes? 
In dogs the most common form resembles Type I diabetes of humans; a reduced production of insulin by the beta-cells is observed due to their destruction. The causes of diabetes are not completely clarified in dogs but it is believed that many factors may contribute, in particular auto-immunity. 
In cats the most common form resembles Type II diabetes of humans; a reduced production of insulin by the beta-cells and a decreased sensitivity of tissues to insulin (insulin-resistance) are observed. In diabetic cats, several studies have shown the importance of obesity as a predisposing factor: other factors are physical inactivity and an unhealthy diet. 
The development of diabetes in dogs and cats can be triggered by different predisposing diseases, such as hyperadrenocorticism (or Cushing), hypersomatotropism (or acromegaly), chronic infections, pancreatic tumors and pancreatitis, and by prolonged administration of particular drugs, in particular corticosteroids and progestogens. 

What are the clinical signs of diabetes? 
The most common clinical signs of diabetes in dogs and cats are the increased urine production and increased thirst (polyuria and polydipsia), excessive appetite (polyphagia) and weight loss. Some cats present a plantigrade gait caused by diabetic neuropathy, and some dogs shows visual impairment due to the development of diabetic cataract. 

How is diabetes diagnosed? 
The diagnosis of diabetes in dogs and cats is made by a combination of hyperglycemia (increased concentrations of glucose in the blood), loss of glucose in the urine (glycosuria), and increased concentrations of fructosamines in the blood. Fructosamines are proteins that bind irreversibly to glucose; they increase during hyperglycemia. 

How is diabetes treated? 
The recommended treatment for diabetes consists in the administration of insulin together with prescription of a low carbohydrate diet. Alternative drugs than insulin, such as some oral hypoglycemics, have shown limited or no beneficial effect in diabetic dogs or cats, therefore they are usually not recommended. 

How is insulin administered? 
Insulin is administered subcutaneously using special syringes. In most cases the administration of insulin needs to be performed twice daily, during or just after the meal. Insulin is a delicate protein; therefore the insulin bottle must be kept in the refrigerator. Due to the fragility of insulin, the bottle must be gently agitated before administration. According to the insulin type, mixing may or may not be required before administration; consult with your veterinarian in case of doubts. 

What is the use of glycemic curves and how are they generated? 
Glycemic curves are necessary to help the veterinarian understanding if the prescribed dose of insulin in diabetic animals is correct. Glycemic curves can be generated by the veterinarian or at home. In the latter, the curve is made by the owner using a portable glucose meter. To generate a glycemic curve, glucose measurements are carried out every 2 hours, during 12 hours. 

How many follow-up evaluation have to be performed by the vet? 
Diabetic animals need to be periodically monitored by the veterinarian to verify if the disease is adequately controlled. The controls are scheduled every week or every two weeks at the beginning, then monthly, and later every three or four months if diabetes is optimally controlled. 

How long can a diabetic animal live and with what quality of life? 
Recent studies showed that diabetic dogs and cats live many years if the disease is well controlled. The quality of life is optimal. However, if complications arise or other diseases develop, life expectancies can be greatly reduced. 

What are the complications of diabetes and what is ketoacidosis? 
The most severe complication in diabetic dogs or cats is the ketoacidosis. Other complications are urinary and skin infections, diabetic cataract (frequent in dogs, rare in cats), and neuropathies. 
Ketoacidosis in dogs and cats develops more frequently if other concurrent diseases are present or if diabetes is poorly controlled. Ketoacidosis is characterized by an excessive production of substances that accumulate in the organism, the ketone bodies. The most frequent clinical signs of ketoacidosis in dogs and cats are weakness, lethargy and vomiting. Frequently, dogs and cats with ketoacidosis are presented to the veterinarian in lateral recumbency, hypothermic and extremely weak. Such cases need an immediate hospitalization in a well-equipped veterinary structure where it is possible to strictly monitor glycemia, pH and blood electrolytes (blood gas analyses), and where it is possible to provide continuative medical cares, 24/24. Ketoacidosis, if not treated with adequate attentions or if the diagnosis is delayed, can cause death. 

What happens if the dose of insulin is too high or hypoglycemia occurs? 
If the administered dose of insulin in a diabetic dog or cat is given in excess, blood glucose drops to low concentrations (hypoglycemia). In some cases, if glycemia is extremely low (below 50 mg/dl) neurological signs can appear, such as tremors and restlessness. In most severe cases (glycemia below 30-40 mg/dl) hypoglycemia can cause seizures. Severe hypoglycemia, if not rapidly corrected, can cause death. A useful advice to promptly correct hypoglycemia, if mild, is represented by the administration of a small additional meal. If the hypoglycemia is severe, it is necessary to give your pet some sugar, preferably honey, applied on his palate or tongue, and contact your veterinarian. 

Is it possible to recover from diabetes? 
Diabetic dogs and cats, after some weeks or months from diagnosis, may no longer require insulin therapy to maintain blood glucose within normal limits. This conditions is called clinical remission of diabetes. The remission is more probable if diabetes is secondary to a treatable predisposing disease (e.g., hyperadrenocorticism). The remission in dogs is rarer than in cats. In general, remission is more likely if diabetes developed recently (1-2 weeks, to 3 months). 
In female dogs, diabetes can appear 1-2 months after estrus, if an imbalance of sexual hormones is present. In this case the ovariectomy (sterilization), if performed right after diagnosis, helps achieving remission of diabetes. 
In cats remission of diabetes can be achieved in more than 50% of cases. Cats with diabetes diagnosed at an older age and cats with normal cholesterol at diagnosis are more likely to achieve remission.

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Frequent questions on Diabetes Mellitus