One might ask the question : Is it important to maintain consistency in the blood glucose concentration, taking into account the fact that many tissues may shift the level of utilization of fats and proteins for energy needs in the absence of glucose? The fact is that glucose is the only nutrient that is normally used by the brain, retina, germinal epithelium of the gonads in quantities sufficient to provide them with the necessary energy, therefore it is important to maintain the concentration of glucose in the blood at a high level that ensures the need for this nutrient.
The largest amount of glucose produced by gluconeogenesis is used between meals for metabolic processes in the brain. In fact, it is important that the pancreas does not secrete insulin during this period, otherwise all the meager amounts of glucose available at that time would enter the muscles and other peripheral tissues, leaving the brain without a source of nutrients.
It is equally important that the concentration of glucose in the blood does not reach very high values, because: (1) glucose can create high osmotic pressure in the extracellular fluid, and if the glucose concentration reaches very high values, this can cause significant dehydration of cells; (2) an excessively high level of glucose in the blood leads to a loss of glucose in the urine; (3) loss of glucose in the urine causes osmotic diuresis, which is accompanied by dehydration and loss of electrolytes; (4) long-term existing hyperglycemia can cause damage to many tissues, especially blood vessels. Vascular injuries combined with advanced diabetes mellitus increase the risk of heart damage, strokes, end-stage renal disease and blindness.
Diabetes mellitus is a symptom complex, manifested by a decrease in the metabolism of carbohydrates, proteins and fats, caused by both a lack of insulin production and a decrease in tissue sensitivity to insulin. There are two types of diabetes.
1. Type I diabetes , also called insulin-dependent diabetes mellitus, is caused by a lack of insulin production. 2. Type II diabetes , also called non-insulin-dependent diabetes mellitus, is caused by a decrease in the sensitivity of target tissues to insulin. Decreased insulin sensitivity is often referred to as insulin resistance.
With both types of diabetes, the metabolism of all major nutrients is disrupted. There is no effect of insulin on glucose metabolism either due to non-production of the hormone or due to insulin resistance of tissues, which impedes the effective intake and use of glucose in most tissues except brain tissue. As a result, the concentration of glucose in the blood rises, glucose consumption uncontrollably decreases against the background of increasing consumption of fats and proteins.