Diabetes mellitus and its signs | Role of glucose in the body | Lab testing
Diabetes mellitus and its signs
In translation from Greek diabetes mellitus (DM) — “to pass through …”. Diabetes mellitus is manifested by fatigue, thirst, excretion of large amounts of urine, leads to relative dehydration and disruption of energy metabolism in the body.
Diabetes mellitus (DM) is divided into two types:
- Type 1 (insulin-dependent) is associated with a lack of insulin, a hormone produced by the B cells of the islets of Langerhans in the pancreas. Under these conditions, the concentration of glucose in the blood rises sharply, unable to penetrate the cells.
- Type 2 (non-insulin dependent) is characterized by the fact that almost enough insulin is produced, but the cells are insensitive to it and glucose also does not have the ability to enter the cells, since insulin has no effect. This phenomenon is called insulin resistance.
There is also so-called “dormant diabetes”, which is only detected by laboratory examination.
Role of glucose in the body
Let’s talk directly about glucose. What role does it play in the body?
Glucose is an osmotically active substance. This means that with an increase in its content in the blood, water from the tissues enters the blood, which leads to relative dehydration (dehydration). To compensate for this dangerous potential effect, the kidneys begin to excrete glucose in the urine (usually 10.0 to 11.0 mmol / L — the renal threshold). In this case, the body loses an important source of energy, which is glucose. Everyone has their own kidney threshold, which is important to know.
Despite significant fluctuations in the intake and utilization of glucose during the day, its blood level usually does not rise above 8.0 and does not fall below 3.5 mmol / L, the normal fasting blood glucose level is 3.5-5-6 mmol / l, not on an empty stomach — 3.5-8.0 mmol / l.
Lab testing
How can diabetes be detected?
Laboratory research methods and their correct interpretation play an important role in the diagnosis of diabetes.
There is a specific algorithm for examining diabetes mellitus. Healthy people with normal body weight and uncomplicated heredity examine the level of glucose in the blood and urine (fasting).
When normal values are obtained, an analysis for glycated hemoglobin (HH) is required. About 5-8% of the hemoglobin found in erythrocytes attaches to itself a glucose molecule, therefore such molecules are called glycated. The degree of glycation depends on the concentration of glucose that is retained in erythrocytes throughout their 120-day life (the norm is 4.5–6.5% of the total amount of hemoglobin). Therefore, at any given time, the percentage of glycated hemoglobin reflects the average level of glucose concentration in the patient’s blood over the 2-3 months preceding the study. When monitoring diabetes therapy, it is recommended to maintain the level of glycated hemoglobin less than 7% and to revise the therapy when the level of GH is 8%.
When a high level of glycated hemoglobin is obtained (screening in a healthy patient), it is recommended to determine the blood glucose level 2 hours after glucose load (75 g). This test is especially necessary if blood glucose levels, although higher than normal, are not high enough to show signs of diabetes. The test is carried out in the morning, after an overnight fast (at least 12 hours). Determine the initial glucose level and 2 hours after ingestion of 75 g of glucose dissolved in 300 ml of water. Normally (immediately after loading with glucose) its concentration in the blood increases, which stimulates the secretion of insulin. This, in turn, reduces the concentration of glucose in the blood, after 2 hours its level practically returns to the initial value in a healthy person and does not return to normal, exceeding the initial values twice in patients with diabetes mellitus.
Once again, I would like to note that it is insulin (a hormone of the pancreas) that is involved in maintaining a constant level of glucose in the blood (the degree of its secretion is determined by the level of glucose). Insulin is essential for differentiating the various forms of diabetes. So, type 1 diabetes is characterized by low insulin levels, type 2 — normal or elevated.
Insulin determination is used to confirm the diagnosis in people with borderline glucose tolerance disorders. Normally, the insulin level is 15-180 ml / l (2-25 mc / l).