Blood sugar balance: Why is it important? How to monitor it?

Author: Wang Xuejing, Chief Physician of Civil Aviation General Hospital

Reviewer: Wu Xueyan, Chief Physician, Peking Union Medical College Hospital

Glucose plays a vital role in the complex physiological mechanisms of the human body. As the main energy substance, its concentration in the body needs to be maintained at a relatively stable level to ensure the normal functioning of various organ systems.

Glucose is converted into ATP (adenosine triphosphate) through aerobic oxidation and anaerobic glycolysis, which is a direct source of cellular energy. In the human body, a highly coordinated organism, the concentration of glucose is precisely regulated to keep fasting blood sugar within a healthy range of 3.6-6.1mmol/L. When carbohydrates in food are digested and absorbed, the glucose level in the blood rises, and the excess glucose is stored in the liver and muscles to form glycogen. When the body is not fed for a long time or is under stress, the liver breaks down the stored glycogen into glucose and releases it into the blood to meet energy needs. It is worth noting that the brain is one of the organs in the human body that relies most on glucose. Even at rest, the brain consumes about half of the total glucose in the body. Therefore, maintaining a stable blood sugar concentration is crucial to ensure brain function.

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Low blood sugar can be caused by a variety of factors, including insufficient intake, malabsorption, excessive consumption, and the relatively rare insulinoma. Insulin is a blood sugar-lowering hormone. When it is secreted excessively, it can lead to hypoglycemia. In addition, if diabetic patients use medication improperly, they may also experience drug-induced hypoglycemia. Hypoglycemia can cause symptoms such as palpitations, dizziness, and sweating. In severe cases, it may cause coma or even death. Especially in newborns, hypoglycemia may cause brain hypoxia and cause irreversible brain damage.

High blood sugar is more common, and its causes are varied, mainly including excessive intake of carbohydrates, insufficient insulin secretion (such as diabetes), certain endocrine diseases (such as hyperthyroidism), etc. Long-term high blood sugar can cause extensive damage to the body, especially to small blood vessels. There are no symptoms in the early stage, and it is a "silent killer." For example, a retina soaked in high sugar can cause diabetic retinopathy, which manifests as decreased vision; kidney tissue soaked in high sugar can also cause cell damage and lead to abnormal kidney function, such as protein in the urine, polyuria, and even oliguria. In addition, high blood sugar can increase the fragility of blood vessels, affect blood circulation, and induce complications such as diabetic foot. Therefore, for people with abnormally high blood sugar, early diagnosis and effective control of blood sugar levels are critical.

In order to accurately monitor blood sugar levels, several methods are used in clinical practice. The most commonly used is to measure fasting blood sugar, which is a blood sugar sample collected after no food has been consumed for at least 8 hours. This indicator reflects the basic functional status of the pancreas and is an important basis for evaluating blood sugar levels. However, since blood sugar is constantly fluctuating due to various factors, it is difficult to fully reflect an individual's blood sugar status based on fasting blood sugar alone. For this reason, doctors also recommend testing glycated serum proteins (mainly glycated albumin) and glycated hemoglobin. The former reflects the average blood sugar level in the past 2-3 weeks, while the latter covers the blood sugar change trend in the past 2-3 months. Both can more stably indicate the effect of blood sugar control and help identify individuals with large blood sugar fluctuations.

For diabetic patients, regular monitoring of blood sugar at different time points can help determine blood sugar control and scientifically adjust medications. In addition to fasting blood sugar, blood sugar two hours before and after meals is also included in the monitoring range. This is because some patients' abnormal blood sugar levels are mainly manifested in specific time periods, such as increased blood sugar after meals. By monitoring blood sugar levels at these key time points, doctors can adjust treatment plans more accurately to ensure that blood sugar is stable within the target range. In addition, nighttime blood sugar monitoring is also indispensable for patients who are adjusting medication dosages or experiencing new symptoms to prevent potential risks of hypoglycemia.

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Portable blood glucose meters for home use provide convenience for daily monitoring. However, in some cases, patients still need to go to the hospital for professional testing. For example, when the blood glucose meter readings do not match the clinical symptoms, the accuracy of the instrument is suspected due to long-term lack of calibration, and the treatment plan needs to be adjusted, a more accurate laboratory test method should be selected.