Diabetes is characterized by persistent hyperglycemia, that is to say too high glucose concentration in the blood. It derives from the disturbance of blood glucose regulation mechanisms in which insulin plays a central role. Diabetes leads to non-specific symptoms as well as many life threatening complications.
Glucose is the main source of energy for the organism. The carbohydrates absorbed from the meals are transformed in glucose, which is readily usable by all the cells in the organism. The brain and the body muscles, including the heart muscle, use most of it. The excess of glucose is transformed into glycogen, a long chain of glucose isomers. Glycogen is stored, as glucose reserve, mainly in the liver, but also in the muscles and, to a lesser extent, in the kidneys.
Insulin is secreted by the beta cells of the pancreas, a small organ close to the stomach. Insulin is both responsible for promoting the transformation of glucose into glycogen and for helping glucose enter into the cells of the body through the otherwise impermeable membranes. These two mechanisms lower glucose concentration in the blood. Insulin’s role is balanced by glucagon, another hormone also produced in the pancreas that acts in the opposite direction. More recently, the roles of other hormones acting in different directions have been unveiled: amylin, GLP-1 peptide, GIP peptide, epinephrine, cortisol, growth hormone and somatostatin.
Diabetes comes from an impairment of the glucose regulation mechanisms. Insulin especially, is no more able to play its role. Either it is not produced in large enough quantities. Or it is no more able to allow a correct utilization of glucose by the cells: it is insulin resistance.
is often split into two categories:
- Type 1 diabetes corresponds to the lack of insulin caused by the progressive destruction of the endocrine part of the pancreas. It concerns mainly dogs. It is a chronic disease.
- Type 2 diabetes is a complex process that involves insulin resistance and insulin secretion impairment within the pancreas. It concerns mainly cats and can be cured if treated soon enough.
Triggering factors of both type of diabetes are not fully elucidated. They include genetic and environmental causes. Obesity increases risk of type 2 diabetes in cats.
Glucose, when present in too high concentration, is toxic to many organs and thus leads first to prediabetes and then to the many symptoms and complications. It is also toxic to the pancreas where it accelerates the progression of diabetes.
Pancreatitis is an inflammation of the pancreas caused by excessive production of digestive enzymes from the endocrine part of this organ. Pancreatitis is involved in many diabetes cases, especially in dogs. Its importance is probably well underestimated because of the difficulty of diagnosis. Every diabetic dog should be screened for pancreatitis.