What is Diabetes?
The term diabetes is defined as a morbid (pathological) condition, characterized by alterations of the water exchange, which occur with an excessive intake of liquids and an increased elimination of urine.
- diabetes mellitus, which is diabetes proper, due to a deficiency or impaired function of insulin;
- diabetes insipidus, caused by a deficient or altered function of the anti-diuretic hormone (ADH);
- steroid diabetes, given by hyper-production of glucocorticoids (cortisol), caused by a disease called " Cushing's syndrome ".
Diabetes mellitus
Diabetes mellitus is a disease that has, as its sole cause, the impaired production or function of insulin.
Insulin is a hormone produced by the endocrine pancreas, which, together with other compounds, is responsible for maintaining blood glucose (amount of glucose in the blood).
The endocrine pancreas, presents various types of cells including:
- α cells dedicated to the production of the glucagon hormone, which stimulates the production of glucose by the liver cells (of the liver), therefore it has a hyperglycaemic effect (increases glycaemia),
- β-cells that produce insulin, which has a hypoglycemic effect (lowers blood sugar), because it determines the uptake of blood glucose (which is found in the blood) by the cells, and inhibits its production by the liver.
The synergistic action of insulin and glucagon therefore makes it possible to regulate blood sugar, keeping it at physiological values ranging from 70 to 110 mg / dl. In a nutshell, when there is a need for glucose (primary energy source) from the cells, glucagon causes it to be produced by the liver and put into circulation (blood glucose increase) and then picked up by the cells, which in this way use thanks to insulin (which causes hypoglycemia).
Consequences
When the animal suffers from diabetes mellitus, the lack of insulin leads to a large deficiency of endocellular glucose (inside the cells), due to the impossibility of the cells themselves to incorporate the glucose found in the blood. As a result of the endocellular glucose deficiency, the cells trigger all those processes that lead to greater glucose production (with even greater glucagon production).
This creates a vicious circle in which the cells are increasingly lacking in glucose and the blood is always richer, so the blood sugar level increases more and more.
The lack of insulin causes the activation in the cell of those mechanisms that lead to the production of energy starting from non-glucidic substrates: fats (glycerol incorporated in the triglyceride molecule) and proteins (which determine the animal's weight loss). Furthermore, there is polyphagia (increased appetite), because insulin is also responsible for the activation of the " satiety center ", which, in the absence of this hormone, is not activated and therefore induces a constant appetite, which determines a further increase in blood sugar.
At the renal level, generally, glucose passes the renal filter and is then reabsorbed, again by the kidney, by the so-called proximal convoluted tubule. If the concentrations of glucose in the blood are excessive (marked hyperglycemia), as occurs in diabetes, the kidney can no longer reabsorb all the glucose, which therefore passes partly into the urine (glycosuria). Being then an osmotically active molecule (recalls water), glucose prevents the reabsorption of water by the kidney, with consequent polyuria (increased emission of urine).
In turn, excessive water loss with urine causes hypotension (low pressure), which, in addition to having a negative effect on various organs, including the kidney, stimulates the animal to take a lot of water (polydipsia ).
Complications
Over time, occasionally in animals that are under therapy, but especially in those where diabetes mellitus has not been diagnosed, therefore not treated, the clinical picture worsens and further complications arise.
Cataract (opacification of the lens with vision loss) is probably the most frequent complication, which occurs in dogs suffering from diabetes mellitus. The alterations of the crystalline lens (part of the eye) occur because the constant hyperglycemia causes an accumulation of glucides in the (crystalline) lenses, which indirectly cause a breakage of the fibers of the lenses themselves.
Diabetic ketoacidosis (DKA) is perhaps the most serious complication that can be found, in the vast majority of cases, in animals in which it was unknown that they were suffering from diabetes mellitus and therefore not undergoing therapy. The prolonged lack of insulin determines, over time, a greater use of lipids to produce energy at the expense of carbohydrates. This leads to the production, then to the accumulation, of ketone bodies in circulation that determine metabolic acidosis (the animal suffers from halitosis: breath that smells like acetone). Then when the ketones reach concentrations that are no longer reabsorbed by the kidney, they flow into the urine (ketonuria), increasing the diuresis and the excretion of electrolytes (sodium, potassium, magnesium). The metabolic alterations caused by DKA can seriously endanger the life of the animal.
Diabetic neuropathy is also a common consequence in cats suffering from diabetes mellitus. Although the cause is still not entirely clear, this complication arises with motor deficits (cats, while walking, support the hocks), weakness, incoordination and lack of reflexes.
Finally, as a consequence of all those metabolic alterations caused by untreated diabetes mellitus, we can have complications such as pancreatitis (inflammation of the pancreas), hepatic lipidosis (accumulation of lipids in the liver), retinopathy (retinal disease), bacterial infections and glomerulonephropathy (pathology of the kidney).
