People with diabetes often chat like this: "My fasting blood sugar is high, and my postprandial blood sugar is high." What do high fasting blood sugar and high postprandial blood sugar indicate?
What does high fasting blood sugar mean?
Fasting blood sugar represents the body's basal blood sugar value, which reflects the basic state of blood sugar maintained through glycogen output after a night of not eating. Therefore, the main factor affecting fasting blood glucose is the decomposition of glycogen, not the secretory function of the pancreatic islets, let alone the reserve function of the islets.
If the fasting blood sugar test result is hyperglycemia, that is, higher than 6.1mmol/L, it means that the subject's basal blood sugar is indeed high, proving that the patient's pancreatic islet function has been damaged to a certain extent and is not caused by eating.
What does high blood sugar after a meal mean?
After we eat, the food passes through the intestines and stimulates the secretion of insulin. The amount of food eaten is the "sugar load". For healthy people with intact pancreatic islet function, although blood sugar rises after eating, due to the rapid secretion of insulin stimulated by food, blood sugar can quickly fall back to the normal range; for diabetic patients, although the same as healthy people eating, However, due to impaired pancreatic islet function, the insulin secretion stimulated by food is not enough to lower blood sugar back to the normal range, and postprandial hyperglycemia occurs.
If your level is higher than 7.8 mmol/L 2 hours after a meal, it means that your pancreatic islet function has been damaged to a considerable extent.
To give a popular example, compare the fasting state to walking on a flat road, and the state after eating to climbing stairs. The pancreatic islets of a healthy person are like a young man, and the pancreatic islets of a diabetic patient are like an old woman.
So when walking on a flat road, both the young man and the old woman can walk; but when climbing stairs, the young man goes up easily, while the old woman may be panting and unable to go up. This is the difference between fasting blood sugar and postprandial blood sugar.
When we test post-meal blood sugar, the time must be strictly controlled, that is, the time should be started from the time the first bite of food enters the mouth, and the test should be performed after 2 hours.
The progression sequence of fasting hyperglycemia and postprandial hyperglycemia
The body's pancreatic islet function in maintaining blood sugar gradually declines in the order from after meals to fasting. When the body's pancreatic islet function has just begun to decline, fasting blood sugar can still remain normal, but postprandial blood sugar has increased.
If the pancreatic islet function is vividly compared to a person's constitution, then fasting blood sugar is equivalent to a resting state, and postprandial blood sugar is equivalent to doing exercises such as climbing stairs.
When our physical condition first begins to deteriorate, we won’t feel very obvious when resting, but we will feel very tired when climbing stairs. When our physical condition further deteriorates, even if we just rest without exercising, we will feel very tired. The same is true for diabetes. When the pancreatic islet function further declines, abnormalities in fasting blood sugar will gradually become apparent.
For diabetic patients, the function of the pancreatic islet has been severely damaged. Fasting blood sugar and postprandial blood sugar must both reach the standard. Grasp with both hands, and both hands must be firm!
