Blood glucose levels indicate the glucose (sugar) content in the blood. Blood sugar is important for human health, because it is an energy supplier for the cells and thus for the whole body. The values depend on various factors such as food intake and can fluctuate during the course of the day. To prevent diseases, it is advisable to have the values checked at regular intervals so that diseases such as diabetes can be treated at an early stage. In this article you will find important information about blood glucose levels: the meaning of the different values as well as the normal values in adults and children.
What are blood glucose levels?
Blood glucose levels describe the sugar content in the blood. It changes constantly during the day due to food intake and it is completely normal that the value fluctuates. Blood glucose levels are lowest in the morning because no food has been eaten during the night, and they rise after a meal.
Blood glucose is responsible for supplying energy to the cells. Glucose is absorbed with food. Passes from the intestine into the blood. In the blood, glucose is transported into the cells with the help of insulin, a hormone produced in the pancreas, and absorbed there. Some diseases influence the regulation of blood glucose levels. So it can be that the pancreas produces too little insulin. The affected person then suffers from diabetes mellitus.
In the case of the measured values, a distinction is made between two types of measurement data: short-term glucose and long-term glucose. If a routine test is performed, the short-term glucose is tested, which indicates the daily fluctuations in glucose levels. With this value, diabetics can recognize whether they are facing hyperglycemia or hypoglycemia and can thus avoid a sugar shock. Long-term glucose, on the other hand, is measured every two to three months. The value can be supportive in the treatment of diabetes, especially in the case of prognosis.
The HbA1c value, also known as glycosylated hemoglobin, plays an important role in the assessment of blood glucose control. This value describes the proportion of the "sugared" red blood pigment in the total hemoglobin. The HbA1c does not only occur in diabetics, but in everyone. The value is based on the average blood glucose concentration – i.e. the higher the blood glucose level over a longer period of time, the higher the HbA1c value. This value can be used to determine the blood glucose level over the past 8 to 10 weeks. In addition to the blood glucose measurement and the glucose tolerance test, both of which will be explained in the following sections, the test of the HbA1c value is considered to be enormously important in diabetes therapy.
How blood glucose is measured?
Blood glucose is measured in the laboratory or by means of portable blood glucose meters. This can be done by a doctor, health care professionals or even the patient himself (after detailed instruction). Since the blood glucose value can fluctuate greatly throughout the day, a single test is not sufficient. Therefore, several measurements must be taken over a longer period of time in order to be sure whether the blood glucose values are permanently too high or too low.
The blood glucose measurement takes place when the patient is fasting. Fasting in this context means before the patient has eaten food. The result is called fasting blood glucose. A light prick is made in the finger or earlobe so that a small drop of blood can be obtained. This drop is applied to a small stick, which is inserted into a blood glucose meter. After about 30 seconds, the device displays the sugar content of the blood being tested. The value can also be determined during a normal blood sample collection.
Detailed and further information on this topic can be found in the article Measuring blood glucose.
Unit of measurement of blood glucose
The blood glucose value can be given in two units of measurement: "millimoles per liter" (mmol/l) or (mmol/l) or "milligrams per deciliter" (mg/dl). In Western Germany, it is common to express the values in milligrams per deciliter, i.e. mg/dl, while in Eastern Germany, the internationally recognized unit of measurement millimoles per liter, i.e. mmol/l, is used. While mg/dl indicates the weight of dissolved sugar particles per volume, the unit of measurement mmol/l indicates the number of particles, i.e. the amount of substance, per volume. It is also important to mention that deviating standard values frequently appear in the specialist literature.
Oral glucose tolerance test (oGTT)
Another measurement is the oral glucose tolerance test (sugar load test). This indicates whether a glucose tolerance disorder is present and is therefore used to diagnose diabetes. At the beginning of the examination, the fasting blood glucose value is first determined. The patient then drinks a precisely measured amount of sugar solution. Two hours later, the patient's blood glucose level is measured to see how high it has risen and how quickly it falls again. If the values are clearly elevated, this indicates diabetes. However, there are also patients who have abnormal sugar values but have not yet developed diabetes. This is then a preliminary stage of diabetes.
Normal blood glucose values (table)
Normal blood glucose values are measured in the fasting state. Fasting means that one has not eaten anything before the test, which is the case, for example, in the morning immediately after getting out of bed. Do not eat for a total of 8 hours beforehand. Also only water is drunk.
Normal fasting blood glucose levels in adults are between 60 – 100 mg/dl (milligrams per deciliter) or. between 3.3 – 5.6 mmol/l (millimoles per liter). Blood glucose levels rise after a meal. Are between 90 – 140 mg/dl resp. 5.0 – 7.8 mmol/l. Children have a different normal blood glucose value than adults. Even among children there are age-dependent differences regarding normal values. In a 1-day-old infant, the values range from 34 to 99 mg/dl and from 2. Day of life the value is between 46 and 81 mg/dl. After that, the same healthy value applies to children, which can be taken from the tables.
Blood glucose values in the oral glucose tolerance test
This table gives an additional overview of the relation of the HbA1c values in the different units of measurement. The HbA1c value describes the average sugar level over the past 8 to 10 weeks. The normal value for a healthy person is 5 to 6%, for a well controlled diabetic 6 to 7% – if the value exceeds this, the diabetic is described as poorly controlled. Since several factors, such as age and personal condition, have an influence on the value, the percentage is never 100% certain.
Conversion tables for blood glucose values
To convert the values into the other unit of measurement, there are the following formulas:
mg/dl x 0.0555 = mmol/l
mmol/l x 18.02= mg/dl
Since the numbers are rounded after the decimal point, there may be slight inaccuracies. There are also tables that can give a quick overview.
Which are blood glucose levels too high?
The values of the blood glucose level in the fasting state are too high, if the value exceeds ≥ 110 mg/dl resp. 6.1 mmol/l is. Then diabetes is suspected. After eating, the blood glucose values are from 140 mg/dl resp. 7.8 mmol/l is too high, indicating, for example, impaired glucose tolerance.
Among the reasons for too high values are the following:
– Diabetes during pregnancy – Hormone disorders caused by tumors in the adrenal medulla – Hormone disorders caused by tumors in the pituitary gland – Pancreatic disease – Hereditary diseases – Side effects of certain medications
If the values of the blood sugar are increased symptoms such as thirst feeling, increased urge to urinate and visual disturbances occur. If it is enormously high, there is a risk of life-threatening coma and also in the long term, too high a value damages the vessels. This can lead to arteriosclerosis, stroke, kidney weakness and loss of vision. This can also result in tie damage, for example to the lower legs and feet.
Which blood glucose values are too low?
The blood glucose value is said to be too low if it is less than 70 mg/dl or less than 3.9 mmol/l. Low blood glucose is initially manifested by hunger, dizziness, fatigue and sweating. If the value is not changed, i.e. no sugar is added, seizures, circulatory collapse, shock and even death can be the result.
If the blood glucose value is too low, this can have the following causes:
– Insulin overdose during diabetes therapy – Overproduction of insulin triggered by tumors in the pancreas – Disturbances in hormone balance – Excessive physical work and low food intake – Malnutrition due to alcohol, fasting or refusal of food – Severe liver damage, for example cirrhosis of the liver – Alcohol consumption on an empty stomach
If people have been suffering from diabetes for a long time, it is possible that hypoglycemia does not manifest itself symptomatically. There are few or no symptoms, which is why it is not possible to react in time. This is why diabetics need to monitor blood glucose levels. Especially if they are physically active and do a lot of sports.
How to lower blood sugar?
There are several ways to lower elevated blood glucose levels. Already an adapted diet with reduced sugar content. An increase in fiber in combination with exercise can lower blood sugar levels. Increasing exercise supports muscle work and requires more energy, which is supplied by glucose in the blood. In addition, there are also medicines that help to lower blood glucose levels. Special drugs for diabetics are called antidiabetics. With the help of insulin injections, diabetics can quickly influence blood glucose levels.
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