There is a common tendency among diabetics to value fasting blood glucose and neglect postprandial blood glucose, which is very unwise. In fact, the latter is no less valuable than the former, and even more important. The two have different meanings and cannot replace each other. Strictly speaking, fasting blood glucose refers to the blood glucose value measured before breakfast the next day after fasting overnight (except water) for 8-12 hours (note: the blood glucose measured before lunch and dinner cannot be called fasting blood glucose), and its normal value is 3.9~6.1 mmol/l.
I. Meaning of fasting blood glucose
It indicates the basal blood glucose level of the patient in the state without dietary load.
It can indirectly reflect the basal insulin secretion level and hepatic glucose output of the patient in the state of no sugar load stimulation.
It can reflect whether the patient can effectively control the blood glucose throughout the night and even the early morning of the next day with the medication the night before, and it is interfered by the dawn phenomenon and Sumujer reaction. Fasting blood glucose is less interfered by other factors and has good repeatability, so it can be used as an important diagnostic indicator of diabetes.
In order to understand the basic function of the islets (i.e. the severity of the disease) and whether the dose of medication on the first night is appropriate, fasting blood sugar should be monitored.
II. Causes of elevated fasting blood glucose
Insufficient dose of medication or excessive food in the evening leads to a significant increase in fasting blood sugar after dinner, before bedtime and the next day. For this kind of elevated fasting blood glucose, patients should increase the dosage of medication appropriately.
Excessive dose of medication in the evening, coupled with the absence of a meal before bedtime, causes hypoglycemia in the night (especially in the early morning), resulting in a subsequent rebound increase in fasting blood glucose (known as the “Sumoje phenomenon” in medical science). For this kind of fasting blood glucose rise, patients should reduce the dose of oral hypoglycemic drugs or insulin before dinner, and take extra meal before bedtime. Dawn phenomenon: After midnight, the secretion of growth hormone, glucocorticoid hormone and other blood sugar-raising hormones in the body increases, and the peak of their secretion usually occurs between the early morning and the morning, resulting in the rise of fasting blood sugar, which is the so-called “dawn phenomenon”.
The best time to measure fasting blood glucose is from 6:00 to 8:00 in the morning, without using hypoglycemic drugs, eating breakfast or exercising before blood collection. If the blood is drawn too late on an empty stomach, the measured blood glucose value will hardly reflect the patient’s treatment effect, and the result may be high or low. The high results are mainly seen in the diabetic patients with obvious “dawn phenomenon”, and the low results are generally believed to be related to long fasting time and insufficient liver glycogen reserves.
Three, 2 hours after meal blood sugar
The “2 hours after meals blood sugar” refers to the first bite from the time, 2 hours after the blood measured on time, the normal value of 4.4 ~ 7.8 mmol / l. If the diabetic patient is being treated, check the blood sugar 2 hours after meals to take the same glucose-lowering drugs or inject insulin as usual.
Fourth, the significance of “2 hours after meals blood sugar”
To a certain extent, it can reflect the reserve function of the patient’s pancreatic B-cells (that is, the ability of food to stimulate additional secretion of insulin by pancreatic B-cells after eating).
It can reflect the appropriateness of eating and the use of hypoglycemic drugs, which cannot be reflected by fasting blood glucose.
It helps in the early diagnosis of type 2 diabetes and reduces missed diagnosis. Because many early diabetic patients have normal fasting glucose and elevated postprandial glucose. This is due to the fact that the patient’s basal insulin secretion is still available, while the large dose of insulin secretion stimulated by meals is reduced.
Postprandial hyperglycemia is also an independent risk factor for chronic complications of diabetes, especially cardiovascular disease, and it has a better predictive value than fasting glucose and glycated hemoglobin for the risk of death in patients with diabetes.
In addition, testing 2 hours postprandial blood glucose does not affect normal medication or injection, nor does it affect normal eating, so it will not cause significant fluctuations in blood glucose due to temporary discontinuation of medication.
V. Why does blood sugar always remain high?
High blood sugar is a difficult problem for many diabetics. This problem is complicated, involving many factors such as diet, exercise, psychology, medication, monitoring, etc., and it is different for each patient, summarized as follows
1.No control of diet
Diet therapy is the basis of diabetes treatment. Diet control not only helps to lower blood sugar, but also controls weight and reduces the dosage of hypoglycemic drugs. Diabetic patients with mildly elevated blood sugar rely solely on diet control to normalize their blood sugar. On the contrary, if the patient does not pay attention to diet control, it is difficult to keep the blood sugar normal even with good drugs.
2.Lack of exercise
Exercise can promote the use of glucose by peripheral tissues such as muscles, consume calories, reduce blood sugar and body weight, and improve insulin resistance. Diabetic patients should choose jogging, brisk walking, tai chi, swimming and other forms of aerobic exercise. Moderate exercise after meals can help reduce postprandial blood sugar.
3.Mood swings
Tension, anxiety, insomnia and other adverse emotions will stimulate the neuroendocrine system, resulting in increased secretion of catecholamines, glucagon and other glucagon hormones, causing blood glucose to rise.
4.Inappropriate use of drugs
Drug selection is unreasonable, for example, Bysampin, Novocain and other drugs with short maintenance time, control postprandial hyperglycemia effect is good, and the fasting hyperglycemia effect is poor, the latter should choose glimepiride, Damacen extended-release tablets, metformin extended-release tablets and other medium- and long-acting hypoglycemic drugs; for example, obese type 2 diabetic patients should be preferred to metformin, and lean type 2 diabetic patients should be preferred to insulin Pro-secretory agents.
Insufficient or excessive dosage of glucose-lowering drugs leads to high blood sugar is well understood, and excessive dosage of glucose-lowering drugs can also cause high blood sugar is a bit puzzling, which is due to low blood sugar can cause sympathetic excitation and glucagon (such as catecholamines, glucagon, etc.) secretion increases, which leads to rebound blood sugar increase. This situation is mostly due to excessive use of hypoglycemic drugs or insulin in the evening and hypoglycemia in the early morning, which is clinically manifested as fasting hyperglycemia.