Article
What is prediabetes or borderline diabetes and does it matter?
Medically reviewed by Dr Sultan Linjawi, Endocrinologist & Diabetes Specialist — December 2025
What Is Prediabetes?
Prediabetes (also called borderline diabetes) describes blood glucose levels that are higher than normal but not high enough for a type 2 diabetes diagnosis. It represents an important warning sign — a window of opportunity — because early changes in lifestyle, nutrition, movement, stress management, and education can delay or prevent progression to type 2 diabetes.
Insulin resistance is the most common underlying cause of prediabetes, but it is not the only cause. Some people have impaired insulin secretion, others have hormonal or genetic contributors, and many have a combination. What matters most is early recognition and structured support to reduce long-term risks.
Curious how prediabetes develops? Join the free Prediabetes & Insulin Resistance Masterclass to understand the science and what you can do now.
Explore key areas of prediabetes
These sections cover the main areas people with prediabetes commonly ask about.
What is Prediabetes?
Prediabetes describes individuals with abnormal glucose blood tests indicating borderline diabetes. People with prediabetes are likely to progress to diabetes in the coming years but are also the most likely to return to normal with the right changes. The underlying problem is insulin resistance — where the insulin receptor changes shape, usually driven by weight gain around the stomach.
What is Metabolic Syndrome?
Metabolic syndrome is a cluster of problems including high blood pressure, insulin resistance, abnormal cholesterol levels, and excess abdominal fat. People with metabolic syndrome are twice as likely to have heart attacks and strokes and five times more likely to develop type 2 diabetes. Its prevalence has increased significantly over the last three decades.
Free Resource: Learn how insulin resistance develops and what you can do to reverse it in our Prediabetes & Insulin Resistance Webinar.
Who Is at Risk of Prediabetes?
Risk factors fall into non-modifiable (cannot be changed) and modifiable (can be improved) categories. Diabetes rates approach 30% in Indian, Middle Eastern, Southeast Asian, and Indigenous populations, compared to 10% in Caucasian populations.
Non-modifiable risk factors
- Family history of diabetes
- Age over 55
- High-risk ethnic background
Modifiable risk factors
- Excess weight, especially around the waist
- Physical inactivity
- Poor diet high in fat, salt, and sugar
- High blood pressure
What Are the Symptoms of Prediabetes?
The most common symptom is… nothing. This is why screening is so important. Some people may experience fatigue, thirst, frequent urination, blurred vision, infections, or slow-healing wounds — but most feel normal while damage is already occurring.
Why Does Prediabetes Develop?
Prediabetes develops when the body cannot maintain normal glucose levels. The most common mechanism is insulin resistance, where the body’s cells stop responding properly to insulin. However, reduced insulin production, hormonal conditions, or genetic factors may also contribute.
Learn more about insulin resistance in our explanation: What Is Insulin Resistance?
Common Symptoms
Many people with prediabetes feel no symptoms at all. When symptoms do occur, they may include:
- Fatigue or low energy
- Increased thirst or urination
- Blurred vision
- Slow-healing cuts or frequent infections
Read more in our dedicated article: Prediabetes Symptoms.
Additional overview: NIDDK – What Is Prediabetes?
[Image Placeholder: Symptoms diagram]
If you’re experiencing any of these symptoms, consider getting tested and joining the free Prediabetes Masterclass.
How Is Prediabetes Diagnosed?
Prediabetes is diagnosed using blood tests that measure fasting glucose, HbA1c, or glucose response after drinking a glucose solution (oral glucose tolerance test). These tests identify impaired fasting glucose (IFG) or impaired glucose tolerance (IGT), both of which reflect abnormal glucose handling.
Diagnostic Ranges
- Fasting glucose: 5.6–6.9 mmol/L (100–125 mg/dL)
- 2-hour OGTT: 7.8–11.0 mmol/L (140–199 mg/dL)
- HbA1c: 5.7–6.4%
Diagnosis should not rely solely on HbA1c, as accuracy varies by age, ethnicity, and certain health conditions.
Explore related articles:
Evidence-based guidelines: NHS – Pre-diabetes
[Image Placeholder: Diagnosis chart visual]
Testing is the first step — but knowing what to do next matters even more. Join the Prediabetes Masterclass to learn the exact actions that reduce your risk.
What Should I Do Next?
If you have symptoms or risk factors for prediabetes, early testing and education can dramatically reduce the risk of progression to type 2 diabetes. Structured lifestyle support, personalised coaching, and consistent monitoring are the cornerstones of prevention.
Explore helpful next steps:
Free Prediabetes & Insulin Resistance Masterclass
A 40-minute evidence-based session taught by Dr Sultan, explaining exactly how prediabetes develops and the most effective steps to reverse or delay progression.
Reserve Your Free SeatFrequently Asked Questions
What is prediabetes?
Prediabetes means your blood glucose levels are higher than normal but not high enough for a diagnosis of diabetes. It includes impaired fasting glucose, impaired glucose tolerance, or elevated HbA1c. Without action, many people progress to type 2 diabetes, but with the right lifestyle changes, glucose levels can return to normal.
What causes prediabetes?
Prediabetes develops when the body becomes resistant to insulin and the pancreas cannot produce enough insulin to compensate. Central weight gain is a major driver. Genetics, ageing, and certain ethnic backgrounds also increase risk.
What are the symptoms of prediabetes?
Most people have no symptoms. Occasionally people may feel fatigued. Symptoms such as thirst, frequent urination, blurred vision or recurring infections usually suggest higher blood glucose and require testing.
Who is at risk of developing prediabetes?
Risk increases with abdominal weight gain, family history of diabetes, older age, physical inactivity, high blood pressure, abnormal cholesterol, unhealthy diet, and higher-risk ethnic backgrounds such as South Asian, Southeast Asian, Middle Eastern, Pacific Islander, African, Hispanic/Latino, and Indigenous communities.
How is prediabetes diagnosed?
Prediabetes is diagnosed using blood tests: fasting plasma glucose, a 75 g oral glucose tolerance test (OGTT), or HbA1c. Values fall between normal and diabetes thresholds depending on the test used.
What are the diagnostic criteria for prediabetes?
Typical cutoffs include: impaired fasting glucose 5.6–6.9 mmol/L (100–125 mg/dL); impaired glucose tolerance 7.8–11.0 mmol/L (140–199 mg/dL) at 2-hours post-OGTT; HbA1c 5.7–6.4% (39–46 mmol/mol), depending on local guidelines.
Can prediabetes progress to type 2 diabetes?
Yes. Without intervention, many people with prediabetes develop type 2 diabetes over several years. The risk is highly modifiable through weight loss, increased physical activity, improved diet, and blood pressure and lipid control.
How often should I be tested if I have prediabetes?
Annual testing is commonly recommended. More frequent testing may be advised if glucose levels rise, if additional risk factors develop, or if symptoms occur.
Can prediabetes be reversed?
Yes—many people normalise glucose levels with weight reduction, healthier eating and increased physical activity. Even a 5% reduction in body weight significantly lowers diabetes risk. Early action offers the best chance of reversal.
Is metformin helpful for prediabetes?
Metformin may be considered for people at higher risk such as younger individuals with obesity, those with rising glucose despite lifestyle changes, or people with a history of gestational diabetes. It works by reducing liver glucose production and improving insulin sensitivity.
