What is glucose | Main indications | How to prepare
A blood sugar test is one of the most commonly used biochemical diagnostic methods. With its help, it is possible to assess the state of carbohydrate metabolism in the body and, accordingly, the nature of the course of metabolic reactions. This is because glucose is the main source of energy for the work of many organs and systems in the human body. Therefore, if its content in the blood changes, then various pathological conditions develop. Let’s talk about this analysis in more detail, as this will enable the person to correctly navigate the doctor’s prescriptions.
What is glucose?
More than 50% of the body’s energy supply occurs as a result of oxidative reactions in which glucose is involved. The main source of its entry into the body is food, which contains carbohydrates. Getting into the bloodstream, and then into the liver, complex carbohydrates are broken down into simple ones (glucose). Partially, glucose can be formed as a result of gluconeogenesis reactions, that is, from fats and proteins. All these processes are under hormonal control.
Thus, the glucose level in the body is a reflection of a number of processes. These include:
- glycogenolysis is the process of splitting complex carbohydrates, which is accompanied by the formation of glucose;
- glycogenesis – the process of formation of glycogen (complex carbohydrate) from glucose;
- gluconeogenesis (see above);
- glycolysis is the process of the breakdown of glucose to the atoms that make up this molecule.
As stated, all of these reactions are controlled by certain hormones. Therefore, the level of glucose can indirectly assess the hormonal balance in the body and identify its possible impairment. The main hormones that participate in these processes are represented by the following:
- insulin. It provides the breakdown of glucose with the formation of energy (hypoglycemia). If its insufficiency is observed (such a condition develops in diabetes mellitus), then the cells of the human body are in a state of energy hunger;
- glucagon (increases the level of glucose in the body);
- growth hormone (also has a hyperglycemic effect);
- thyroid-stimulating hormone (causes hyperglycemia);
- thyroid hormones – thyroxine and triiodothyronine (also has a contra-vascular effect);
- cortisol (exhibits a similar effect);
- adrenaline (also applies to contra-hormonal hormones).
Venous blood is used to do a blood test, but glucose in arterial and venous blood is different.
Usually blood from a vein is used to do a blood test. However, it should be borne in mind that the concentration of glucose in arterial and venous blood is different. This is due to the fact that cells constantly consume this energy substance, therefore the blood flowing from them (venous) always contains less glucose. Normally, urine glucose should not be excreted. If this condition is observed, then this indicates that the level of glucose in the blood is quite high and exceeds the filtration threshold. The filtration threshold is such a concentration of glucose in the blood at which it passes through the membrane of the renal glomeruli, and, accordingly, appears in the urine. Typically, the filtration threshold is 10 mmol / L.
The main indications for determining blood glucose
The main indication when it is necessary to check blood sugar is the diagnosis of diabetes, that is, absolute or relative insulin deficiency. Using this study, it is possible to determine both diabetes mellitus of the first type (insulin-dependent) and the second (non-insulin-dependent). Given the increasing incidence of this disease, the following people are at risk, who are shown to determine blood sugar levels:
- persons over 45 years old;
- overweight people;
- large children at birth (all 4 kg or more);
- burdened heredity for this disease.
- pathology of the organs of the endocrine system, especially the adrenal glands and the thyroid gland;
- pathology of the liver, which is accompanied by a failure of this organ;
- pregnancy;
- suspicion of a hormonally active oncological process in the body.
How to prepare for the study?
Many people are interested in the question of where blood is taken for sugar, how to prepare for the study, and other questions.
In order to get reliable results, you must adhere to a normal diet the day before. It is considered a mistake to exclude foods containing easily digestible carbohydrates the day before the test. This will distort the actual state of carbohydrate metabolism, as the results will be lower than real (we are talking about diabetes).
A blood test should be done on an empty stomach.
It is also important to consider that fasting blood donates blood for sugar, therefore, you should not eat in the morning before the test. The optimal time for taking the analysis is the interval between 8 and 11 in the morning. You should be aware that a long hunger (more than 14 hours) or too short a gap between food and blood sampling (less than 8 hours) can distort the results. If it takes more than 14 hours after eating, the body begins to experience energy hunger, which leads to the activation of those processes that increase blood sugar.
Blood for analysis can be obtained both from a vein (intravenous injection) and from a finger (in this case, capillary blood is obtained). Normal sugar values in these two cases will differ, which must be taken into account when interpreting the results of the study. An express blood sugar test can also be performed. It implies the use of a glucometer for this purpose, while capillary blood is analyzed.