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Hba1c: what is a normal blood sugar level?


Normal blood sugar levels are difficult to maintain for a great proportion of the world’s population. A total of 422 million people worldwide suffer from diabetes. The majority of them struggle with severe blood sugar fluctuations and associated effects on the neurological and cardiovascular systems. The good news is, with exercise, the right food and fasting, you can get your values under control!

Be it gummy bears, liquorice or chocolate, sweets have long been suspected of triggering diabetes. But it is not necessarily the sugar that results in diabetes. As research has now revealed, a generally unhealthy diet and obesity increase blood sugar levels and cause type 2 diabetes mellitus. Even healthy, athletic children and adults can develop type 1 diabetes, which is usually caused by genetic factors.

Increased blood sugar and diabetes risk can be measured with the long-term blood sugar value HbA1c. Read on to discover what this value is all about and what you can do to avoid hyperglycaemia or hypoglycaemia.

What’s diabetes mellitus?

The long-term blood sugar value HbA1c is particularly relevant for people who suffer from diabetes, also known as diabetes mellitus. According to the World Health Organization (WHO), diabetes mellitus is one of the most common diseases, with around 422 million people living with diabetes worldwide. Type 2 diabetes is particularly prevalent among older people.

In order to really understand the clinical picture of this drastically widespread disease, it is important to be able to classify the most important terms used when talking about diabetes – namely, pancreas, insulin, blood sugar, type 1 diabetes and type 2 diabetes.

What is insulin and what does it do in the body?

The pancreas produces the hormone insulin. It regulates blood sugar – that is, the glucose content in the blood, and opens the cell membrane from the outside, so that the sugar from the blood can enter the cell and supply it with energy. Once the sugar is present in the cell, the sugar content in the blood drops.[1]

Generally, insulin allows the sugar to enter the cells. In the case of diabetes mellitus, the body cannot transport the sugar in the blood into the cells. The sugar (glucose) continues to circulate in the blood, causing the blood sugar to increase. Diabetes is caused by insulin deficiency or unusable insulin. There are three different forms:

  • Diabetes mellitus type 1: absolute insulin deficiency
  • Diabetes mellitus type 2: relative insulin deficiency
  • Gestational diabetes: relative insulin deficiency in pregnancy

Type 1 vs type 2 diabetes: what’s the difference?

In the case of type 1 diabetes, the pancreas no longer produces insulin because it is impaired by viral infections or genetic predispositions. Type 1 diabetes affects children and adolescents; type 2 diabetes, on the other hand, is more likely to be the result of an unhealthy diet and obesity. With this disease, the pancreas produces insulin but cannot open the cell membrane. Fat cells stand in the way of insulin. This is why glucose remains in the blood and blood sugar rises.[2]

Diabetes risk due to vitamin D deficiency

There is a north-south divide in Europe with regard to diabetes type 1. In Scandinavia, significantly more people are affected than in southern Europe. Researchers assume that genetic causes are responsible and vitamin D deficiency, which is widespread in northern Europe. The vitamin D, also known as the sunshine vitamin, is supposed to protect the pancreas from infections that weaken its function.[3]

Read more about vitamin D deficiency in our Health Portal.

Hba1c and pregnancy: gestational diabetes

Gestational diabetes is relatively common. In most cases, elevated blood sugar levels occur within the second half of pregnancy. The following factors increase the risk of the pregnant woman developing type 2 diabetes during pregnancy:[4]

  • Severe obesity
  • Diabetes in a previous pregnancy
  • Family history of type 2 diabetes

It is therefore important to undergo regular medical examinations. If you are diagnosed with gestational diabetes, check your blood sugar levels. After the birth of the child, this form of diabetes usually resolves itself.[5] In the worst-case scenario, poorly adjusted gestational diabetes can lead to miscarriage. 

Breastfeeding and type 2 diabetes

The German Institute of Nutrition Research investigated the risk of developing type 2 diabetes in breastfeeding mothers. The study found that non-breastfeeding participants exhibited a stronger tendency to develop the disease.[6] Researchers at the German Center for Diabetes Research suspect that breastfeeding protects women from type 2 diabetes when they have had gestational diabetes.[7]

Blood sugar and HbA1c

Sugar is like fuel for the body. Our brain, muscles and organs work at full speed when insulin feeds them with this energy source. Bread, potatoes, rice, fruit and sweets contain carbohydrates, chemical sugar chains. They are made up of glucose or fructose, which is converted into glucose in the body. Even in the mouth, substances in saliva break down long-chain carbohydrates into glucose molecules. Only in this form can the body introduce carbohydrates into the bloodstream via the mucous membrane of the small intestine – blood sugar increases, and the pancreas releases insulin.

What is a normal blood sugar level?

Physicians usually measure blood sugar in the international unit millimole per liter (mmol/L). Whether you have normal blood sugar levels depends on whether you are fasting or have eaten.[8, 9]

State of health/ target values at specific times

After getting up (fasting)

Before eating

At least 90 minutes after eating

Normal blood sugar level


72–108 mg/dl

< 140 mg/dl

Type 2 diabetes


72–126 mg/dl

< 153 mg/dl

Type 1 diabetes

90–126 mg/dl

72–126 mg/dl

90–162 mg/dl

Children with diabetes

72–126 mg/dl

72–126 mg/dl

90–162 mg/dl

Modified by: National Institute for Health and Care Excellence

To convert the blood sugar value from mg/dl to mmol/L, you must divide the value by 18. A total of 72 mg/dl therefore results in 4 mmol/L.

The consequences of blood sugar imbalances

It is difficult for a diabetic to maintain consistently normal blood sugar levels. However, with the right therapy and lifestyle, you can aim for healthy blood sugar levels to avoid the consequences of blood sugar fluctuations. Both hypoglycaemia and hyperglycaemia have a negative effect on your body.

If your blood sugar drops to a very low level, this can lead to seizures in addition to the usual symptoms. In the worst case, severe hypoglycemia can cause you to lose consciousness.[15]

Hyperglycaemia for an extended period of time is associated with long-term damage. Damage to the nerve cells causes numbness, especially in the feet. Saccharified molecules are increasingly deposited in the eye, which can lead to impaired vision. High blood sugar levels also make it difficult for the kidneys and heart vessels to cope. The risk of developing kidney problems or even suffering a stroke is higher as a result.[16]

How does high blood sugar affect the brain?

According to the latest research, your brain ages faster if you are suffering from diabetes with continuous hyperglycaemia. In the study, the brain of a diabetic was five years older than that of a healthy volunteer. Similarly, diabetes can promote the onset of dementia. In order to reduce the risk, patients should try to achieve continuously normal blood sugar levels with the right treatment.[19]

What constitutes an elevated blood sugar level?

Physicians consider elevated blood sugar to be present when fasting blood sugar exceeds 126 milligrams per decilitre. Since the body releases considerable amounts of the stress hormone cortisol in the morning, the fasting blood sugar can be greater than 126 mg/dl in the morning. Cortisol increases the amount of glucose in the blood.[10, 11]

American Michael Buonocore was hospitalised in 2008 with a blood sugar level of 2656 mg/dl. He was diagnosed with type 1 diabetes.[12]

What is Hba1c?

The long-term blood sugar HbA1c indicates your average blood sugar level over the three months. Sugar attaches itself to the blood pigment haemoglobin in the blood, causing it to saccharify. We call the sugared blood pigment glycohemoglobin, haemoglobin A1c or HbA1c.

The higher the HbA1c value, the more saccharified haemoglobin particles in the blood. This means that you have had increased blood sugar levels during this period.

Which HbA1c values are normal?

HbA1c value


< 5.7 per cent

Normal range

5.7 per cent < 6.5 per cent

Grey area (prediabetes) – this should be clarified

= 6.5 per cent

Increased range (possible diabetes) – this must be clarified

6.5–7 per cent as a normal range for diabetics

If your HbA1c value lies within the grey range, physicians speak of prediabetes. In this blood sugar range, the risk of developing diabetes is higher. This is especially the case for people who are overweight and have an unbalanced diet. A healthy diet and sufficient exercise can minimise this risk. If your value is greater than or equal to 6.5 per cent, physicians will assume that you have diabetes. A comprehensive blood test will enable physicians to confirm the diagnosis.

The blood sugar value indicates how much glucose there is in the blood. The HbA1c value serves as a long-term memory for our sugar content in the blood. It provides information about the blood sugar level of the last three months. Both parameters are important in the diagnosis of diabetes mellitus and are particularly relevant for diabetics.

What are the causes of hyperglycaemia and hypoglycaemia?

Various factors cause blood sugar to increase or decrease. Normally, hormones restore balance to these fluctuations. However, this only works to a limited extent for diabetics. As a result, their blood sugar balance fluctuates more, causing them to suffer more frequent episodes of hypoglycaemia and hyperglycaemia.

What causes hypoglycaemia?

If the amount of insulin is too high, the blood sugar level drops rapidly. Too much sugar enters the cells. The following conditions reduce your blood sugar level considerably:[14]

  • Use of more insulin and medication than necessary
  • Extensive physical activity
  • High stress levels
  • Heavy alcohol consumption
  • Fasting and omitting meals (especially in type 1 diabetes)

You should not underestimate hypoglycaemia: decreasing blood sugar levels must be counteracted. Always carry your glucose meter and dextrose with you to avoid the dangerous consequences of hypoglycaemia.

In rare cases, benign tumours can also lead to hypoglycaemia. Insulinomas produce excess insulin, which causes the blood sugar level to drop. People over 50 years of age are especially affected.[15]

What increases blood sugar levels?

Hyperglycaemia mainly affects diabetics. Glucose remains in the blood due to a lack of insulin. Blood sugar levels can also increase due to:[16]

  • High stress levels
  • Use of cortisone preparations
  • Infections
  • Lack of exercise

Hypoglycaemia and hyperglycaemia symptoms

Fluctuations in blood sugar levels don’t go unnoticed. Your heart races, confusion sets in and your emotional state fluctuates between anxiety and anger. Hypoglycaemia and hypoglycaemia can be dangerous if you fail to act promptly. The problem with blood sugar imbalances is that the more often you suffer from them, the more prominently you may feel them over time. People with frequent hypoglycaemia notice that their blood sugar is low either too late or not at all, which can have life-threatening consequences.[17, 18]

What does it feel like when your blood sugar is too high?



Heart races

increased urination

Ravenous appetite

increased thirst

Difficulty concentrating, fatigue, confusion, anxiety attacks, emotional outbursts


increased sweating, chills, weak knees


How do I optimise my blood sugar and HbA1c level?

how to maintain normal blood sugar level

Regular examinations by doctors and diabetologists are important for an optimal HbA1c value. However, a great deal of responsibility also lies with those affected. The right insulin and medication therapy can be used to adjust blood sugar levels very well. However, in the event of fluctuations in blood sugar levels, patients must act correctly to prevent health problems. Ideally, not only the diabetic, but also family members, friends and partners should be informed.

Hypoglycaemia episode: what to do

You need to act fast! Hypoglycaemia is best treated with quickly absorbed sugars: dextrose, sweets, Coca Cola and juices. Depending on the value, it is recommended that you use the following remedies. After 15 minutes, you should check whether the value has increased.[20]

Blood sugar


Coca Cola



< 80 mg/dl

1 tablet

50 ml

1 tsp diluted in water

100 ml

< 70 mg/dl

1. 5 tablets

75 ml

1.5 tsp diluted in water

150 ml

< 60 mg/dl

2 tablets

100 ml

1 tbsp diluted in water

200 ml

< 50 mg/dl

2.5 tablets

125 ml

1.5 tbsp diluted in water

250 ml

What should I do if my blood sugar does not increase?

You should not be alone if you are not able to increase your blood sugar level. Here is what you should do:[21]

  • Get help: tell your partner, neighbour or a person in your immediate vicinity
  • Continue to consume quickly absorbable carbohydrates and check your values every 15 minutes
  • If the value drops significantly, contact 999
  • Always have a glucagon syringe handy; glucagon is the antagonist of insulin and increases blood sugar

How can I lower high blood sugar levels?

You can counteract high blood sugar with insulin. Your diabetologist will discuss with you the amount of insulin that is needed with hyperglycaemia. Exercise can lower your blood sugar, but if you develop hyperglycaemia, your blood sugar will increase considerably as a result of exercise.[22]

How to lower Hba1c values

With the right medication and lifestyle, you can improve your HbA1c value and keep it at an optimal level. This is especially important for people who suffer from diabetes. As a diabetic, you should check your HbA1c every three months and your blood sugar levels several times a day. Continue to eat a healthy diet. In many cases, type 2 diabetics are able to control their illness so well by changing their diet and losing weight that they only take few or no medication at all.[23, 24, 25]

Type 1 diabetes

Type 2 diabetes

Adjust insulin treatment correctly

Adjust insulin and medication correctly

Exercise regularly

Exercise regularly, lose weight

Avoid foods with a high glycaemic index

Avoid foods with a high glycaemic index, eat healthily

Check blood sugar regularly

Discuss continuous blood sugar monitoring with your physician

Check blood sugar regularly

Check HbA1c value every three months

Check HbA1c value every three months

How does magnesium lower blood sugar?

Magnesium supplements can help type 2 diabetics get their blood sugar under control; it is considered one of the best supplements you can take as a type 2 diabetic. This is because the mineral promotes the effectiveness of insulin. This allows the body to transport more sugar into the cells.[26]

To find out more about magnesium – particularly about magnesium deficiency – head over to our Health Portal article now

Glycaemix index: what is it?

The glycaemic index indicates how quickly and how strongly blood sugar rises when you consume a certain foodstuff. The higher and faster your blood sugar increases, the more insulin your body needs. For example, white flour products, white rice, pumpkins and sweets are foods with a high glycaemic index. Wholegrain products and most fruits do not cause blood sugar levels to increase as drastically.[27]

Can diabetes be reversed with fasting?

Intermittent fasting is becoming increasingly important. During the day, you should have a fasting period of 16 hours, during which you may only drink water and tea. You can only eat for the remaining eight hours. The most popular method is to eat two meals between 12 and 8 p.m. and then fast. According to a study in the World Journal of Diabetes, intermittent fasting can help type 2 diabetics improve their blood sugar levels and lose weight. The long phases of not eating will immobilise your blood sugar and your metabolism will go to your fat reserves. Remember, as soon as your pancreas releases insulin, your fat metabolism is stopped.[28, 29]

How does exercise affect diabetes?

If you are exercising, you should check your blood sugar one hour beforehand. If the value is less than 100 milligrams per decilitre, you should eat two tablets of dextrose or a banana. If the value is above 200 milligrams per decilitre or below 80 milligrams per decilitre, you will need to wait for the value to normalise. It is also best to check your blood sugar level after exercise, as you usually do not notice a hypoglycaemia episode when working out.[22]

Please note: You should not only check you have normal blood sugar levels before exercising, but also before driving a vehicle!

Can I test my own HbA1c?

banner of hba1c blood test

The HbA1c value is the most important parameter for examining the current blood sugar level of a diabetic. In addition to diabetics, people at high risk of diabetes should have their blood sugar levels checked. If you are overweight with a family history of diabetes, it is also a good idea to monitor them.

An HbA1c test is beneficial for the following reasons:[30]

  • You don’t have to administer it on an empty stomach
  • It can be checked at any time
  • It provides information about your blood sugar over the last three months
  • It only requires a small amount of blood

Who can check your HbA1c value?

Family doctors, diabetologists and some pharmacists are able to check your long-term blood sugar levels, but you can also do a test at home. With an HbA1c test, take a small amount of blood from your fingertip. A specialist laboratory then usually analyses your blood sample to determine your long-term blood sugar and uses it to find out your average blood sugar level from the last three months.

HbA1c blood sugar value – at a glance

What is the HbA1c value?

The HbA1c value is also referred to as long-term blood sugar. It provides information on the average blood sugar level over the last three months.

What does the HbA1c value indicate?

If the HbA1c value is above 6.5 per cent, your blood sugar is too high. You may suffer from diabetes. With a value of 5.7 to 6.5 per cent, your risk of diabetes is higher. Diabetes mellitus is a condition that is associated with imbalances in the blood sugar. This is caused by a lack of insulin.

How can I lower my HbA1c value?

In order to optimise your HbA1c value, we recommend regular physical activity, a balanced diet, well-adjusted medication and regular blood sugar and HbA1c monitoring. Intermittent fasting is supposed to help type 2 diabetics to achieve normal blood sugar levels, according to the latest studies.

What are hypoglycaemia and hyperglycaemia?

Hypoglycaemia occurs when an excess of insulin causes the glucose level to drop. Extreme physical activity can also decrease blood sugar. Hyperglycaemia occurs when there is not enough insulin in the body or when you are stressed. If you are hypoglycaemic, you will be less likely be able to concentrate, your knees will become weak and you notice increased sweating. Hyperglycaemia is identified through an increased urge to urinate and a strong feeling of thirst.


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  21. Blauw, H., Wendl, I., DeVries, J.H., Heise, T., Jax, T., PCDIAB consortium: Pharmacokinetics and pharmacodynamics of various glucagon dosages at different blood glucose levels. Diabetes Obes. Metab. 18, 34–39 (2016). doi:10.1111/dom.12571
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