Introduction

Prediabetes is easy to overlook because many people feel completely well. There may be no obvious pain, no dramatic change in energy and no clear signal that blood glucose has moved outside the healthy range.

That is exactly why awareness matters. Prediabetes means blood glucose levels are higher than normal but not yet high enough to meet the diagnostic range for type 2 diabetes. It is an important opportunity to identify increased risk before diabetes develops.

Prediabetes does not mean that type 2 diabetes is inevitable. NIDDK notes that not everyone with prediabetes develops type 2 diabetes, and people can take steps to lower their risk.

The key is not waiting for symptoms. Knowing your risk factors and having appropriate blood testing when recommended can identify prediabetes much earlier.

Blood glucose is an important source of energy. Insulin, a hormone produced by the pancreas, helps glucose move from the bloodstream into cells where it can be used.

Insulin resistance occurs when cells in muscles, fat and the liver do not respond to insulin as effectively as they should. The pancreas may initially compensate by producing more insulin, but over time blood glucose can rise.

When glucose levels become higher than normal but remain below the diagnostic threshold for diabetes, this is called prediabetes.

Prediabetes is not simply a minor laboratory finding. It indicates an increased risk of developing type 2 diabetes and is a reason to pay closer attention to lifestyle, risk factors and follow-up testing.

The title of this article refers to warning signs, but the most important fact is that prediabetes usually has no symptoms. NIDDK states that people with insulin resistance and prediabetes usually do not have noticeable symptoms.

Some people may develop symptoms similar to diabetes when blood glucose becomes more elevated, but symptoms cannot reliably tell you whether you have prediabetes.

Classic symptoms associated with high blood glucose and diabetes can include increased thirst, frequent urination and unexplained weight loss. If these occur, appropriate medical testing is important because glucose levels may already be in the diabetes range.

Feeling normal therefore does not guarantee that blood glucose is normal. For people with relevant risk factors, screening is much more useful than waiting for a physical warning sign.

Prediabetes becomes more likely when risk factors for type 2 diabetes are present. Age, family history, body weight, physical activity and previous glucose problems can all influence risk.

NIDDK advises that healthcare professionals may consider testing adults aged 35 or older, as well as younger adults with overweight or obesity who have additional risk factors for prediabetes or type 2 diabetes.

A history of gestational diabetes can also affect future diabetes risk. Other factors may include having a close family member with diabetes, certain metabolic conditions or belonging to populations with a higher prevalence of type 2 diabetes.

Having one or more risk factors does not mean you definitely have prediabetes. It means testing may be more important because symptoms alone are unreliable.

Healthcare professionals diagnose prediabetes using blood tests. Common options include the A1C test, fasting plasma glucose test and oral glucose tolerance test.

The A1C test reflects average blood glucose over approximately the previous three months. It does not normally require fasting, which can make it convenient for screening.

A fasting plasma glucose test measures glucose at a particular point in time after fasting for at least eight hours. An oral glucose tolerance test measures how the body handles a glucose load over a set period.

These tests do not always identify exactly the same people. A healthcare professional can interpret results alongside your medical history and decide whether repeat or additional testing is needed.

For non-pregnant adults, NIDDK lists an A1C of 5.7% to 6.4% as the prediabetes range. An A1C below 5.7% is considered below the prediabetes threshold, while 6.5% or above falls in the diabetes range and generally requires appropriate confirmation.

For fasting plasma glucose, the prediabetes range is 100 to 125 mg/dL. A fasting result of 126 mg/dL or above is in the diabetes range.

For a two-hour oral glucose tolerance test, 140 to 199 mg/dL is the prediabetes range, while 200 mg/dL or above is in the diabetes range.

Test interpretation is not always straightforward. A1C can be affected by certain blood disorders, anaemia, kidney disease, recent blood loss and other conditions. Pregnancy also requires different considerations.

For this reason, laboratory numbers should be interpreted by a qualified healthcare professional rather than used as a stand-alone self-diagnosis.

Prediabetes is a warning, but it is also an opportunity. NIDDK states that many people can take steps to prevent or delay prediabetes and type 2 diabetes.

Regular physical activity, a nutritious eating pattern and weight management when appropriate can all be part of reducing risk. The right approach depends on the individual rather than following a crash diet or extreme exercise plan.

Physical activity can begin with something as accessible as regular walking and gradually build toward recommended activity levels. Meals can emphasise vegetables, whole grains, legumes, fruit and appropriate protein sources while limiting excessive amounts of highly processed foods and sugary drinks.

For people with overweight or obesity, modest weight loss may be recommended as part of a structured diabetes-prevention approach. However, body weight is only one factor and should not become the sole focus of care.

Because prediabetes usually has no symptoms, screening decisions are often based on age and risk rather than how you feel.

NIDDK notes that healthcare professionals may order testing if you are age 35 or older, or if you have overweight or obesity plus other risk factors. Testing may also be appropriate at younger ages depending on individual circumstances.

If your results show prediabetes, follow-up is important. NIDDK states that people with prediabetes should generally be tested for type 2 diabetes every year, although your healthcare professional may recommend a different schedule based on your situation.

If you develop symptoms associated with significant hyperglycaemia — such as marked thirst, frequent urination or unexplained weight loss — do not wait for a routine screening appointment. Seek medical assessment.

Prediabetes Is Not the Same as Diabetes

Prediabetes and diabetes describe different glucose ranges. Prediabetes means glucose is elevated but has not reached the diagnostic threshold for diabetes.

This distinction matters because discovering prediabetes creates an opportunity to reduce future risk. At the same time, it should not be dismissed simply because it is “not diabetes yet.”

Follow-up testing can show whether glucose levels are improving, remaining stable or progressing. Your healthcare professional can also assess related health factors such as blood pressure, cholesterol and overall cardiovascular risk.

Do Not Wait for a Warning Sign

One of the biggest misconceptions about prediabetes is that your body will clearly tell you when something is wrong. In reality, many people discover it only through routine blood testing.

That makes prevention less about watching for a particular symptom and more about understanding risk. Know your family and medical history, stay physically active, build a balanced eating pattern and attend appropriate health screening.

If a test shows prediabetes, treat the result as useful information rather than a reason to panic. Early action and appropriate follow-up can make a meaningful difference.