Diabetes is one of the most common chronic diseases worldwide. Nevertheless, millions of people do not even know they have it. Type 2 diabetes can develop over several years without a person noticing any significant changes. Meanwhile, elevated blood glucose levels may already be damaging blood vessels, nerves, and various organs.
World Diabetes Day is observed on November 14. It is a good opportunity to understand why diabetes can go unnoticed, what happens in our bodies during the disease, and whether it is possible to prevent it.
What happens in the body when we have diabetes?
Every time we eat, some of the carbohydrates in our food are converted into glucose. Glucose is one of the body’s main sources of energy, but its uptake by cells requires proper regulation.
Insulin, a hormone produced by the pancreas, plays a key role in this process.
We can think of insulin as a key that helps cells take up glucose from the bloodstream. The actual process is more complex, but this analogy helps explain its main function.
In type 1 diabetes, the immune system mistakenly destroys the pancreatic cells responsible for producing insulin. As a result, the body develops a significant insulin deficiency, and the person needs to receive insulin from an external source.
In type 2 diabetes, the problem develops differently. The body’s cells no longer respond properly to insulin. This is known as insulin resistance. Initially, the pancreas tries to compensate by producing more insulin, but over time, this may no longer be sufficient.
As a result, blood glucose levels rise.
Why can diabetes go unnoticed?
Imagine someone who works, exercises, carries out everyday activities, and feels perfectly healthy. Nevertheless, their blood glucose levels may already be elevated.
Type 2 diabetes often develops slowly. The body adapts to elevated glucose levels for a certain period, which is why symptoms may be barely noticeable or very mild.
Some people experience increased thirst, frequent urination, fatigue, or temporary blurred vision. Others have no symptoms at all.
That is why diabetes is sometimes discovered entirely by chance during a routine health check-up.
Prediabetes deserves particular attention. It is a condition in which blood glucose levels are higher than normal but have not yet reached the diagnostic threshold for diabetes.
Prediabetes does not always progress to type 2 diabetes. Lifestyle changes can sometimes prevent or delay the development of the disease.
How dangerous is a disease that causes no symptoms?
One of the main paradoxes of diabetes is that the absence of symptoms does not necessarily mean that a person is healthy.
Prolonged elevated blood glucose levels can damage the inner lining of blood vessels. Small blood vessels are particularly vulnerable, including those supplying the retina, kidneys, and nerve tissue.
For example, diabetic retinopathy can impair vision, while kidney damage can lead to a gradual decline in kidney function. Nerve damage may cause numbness, tingling, or reduced sensation, particularly in the feet.
Diabetes also increases the risk of heart attack and stroke.
These complications are not inevitable. Early diagnosis, blood glucose monitoring, and appropriate treatment significantly reduce the likelihood of developing them.
252 million people who do not know they have diabetes
International statistics clearly illustrate the scale of the problem.
According to the International Diabetes Federation’s 2025 Diabetes Atlas, approximately 589 million adults aged 20–79 worldwide have diabetes. Of these, around 252 million, or 43%, are unaware of their diagnosis.
This means that nearly one in every two adults living with diabetes does not know they have the disease.
Another interesting issue emerged from an international survey published in November 2026: only 15% of respondents at high risk of developing type 2 diabetes believed they could personally develop the condition.
Furthermore, 67% of respondents mistakenly believed that prediabetes usually causes noticeable symptoms.
That is why the main message of World Diabetes Day 2026 is “Early action against diabetes.” The campaign focuses on early detection and reducing risk factors.
How can we detect diabetes early?
There are several relatively simple laboratory tests that can help detect diabetes.
One of them is the glycated haemoglobin test, also known as HbA1c. It shows the average blood glucose level over approximately the previous two to three months.
An HbA1c level of 5.7–6.4% falls within the prediabetes range, while a level of 6.5% or higher indicates diabetes. In people without symptoms, repeat or additional testing is generally needed to confirm the diagnosis.
Other diagnostic methods include fasting blood glucose testing and the oral glucose tolerance test.
Risk assessment is particularly important for people who are overweight, have a family history of diabetes, high blood pressure, or other metabolic risk factors.
The need for and frequency of testing should be determined in consultation with a doctor, taking age and individual risk factors into account.
Can diabetes be prevented?
Type 1 and type 2 diabetes differ not only in how they develop but also in terms of prevention.
There is currently no widely available, reliable method for preventing type 1 diabetes. In the case of type 2 diabetes, however, lifestyle plays an important role. Regular physical activity, a balanced diet, avoiding tobacco, and losing weight when necessary can reduce the risk of developing the disease.
At the same time, diabetes is not simply a consequence of lifestyle. Genetic predisposition, age, and other biological and environmental factors also contribute to its development.
The main message of World Diabetes Day is precisely this: we should not wait until our bodies send us obvious warning signals before taking steps to detect the disease.
Sometimes, a routine blood test can be the first step towards preventing complications that may otherwise develop unnoticed over many years.
