Prediabetes: Signs, Blood Test Results and How to Reverse It

Prediabetes has become one of the most common preventative health issues we manage. The condition now affects millions of people across the UK, but it represents a critical window of opportunity. It is a warning signal from your body that, if heeded, can allow you to prevent or significantly delay the onset of type 2 diabetes.

Prediabetes is a health condition where your blood sugar levels are higher than normal, but not yet high enough to be diagnosed as type 2 diabetes. For many, it's a silent condition with no obvious symptoms, which makes understanding your personal risk factors absolutely crucial for early detection and intervention. Without changes to lifestyle, many people with prediabetes will go on to develop type 2 diabetes.

This guide is for you if you have recently been told you have prediabetes, are worried you might be at risk, or want to support a loved one through their diagnosis. It provides a comprehensive, medically-reviewed plan to help you navigate this condition with confidence. You will learn what prediabetes is, how to interpret your blood test results, a step-by-step action plan to reverse it, and what to expect on your journey back to healthier blood sugar levels.

What is prediabetes?

Prediabetes is a health condition where your blood sugar levels are consistently higher than normal, but not yet high enough to be diagnosed as type 2 diabetes. It's an intermediate stage where your body is struggling to regulate glucose (sugar) effectively.

Insulin and insulin resistance

To understand prediabetes, it’s helpful to know how your body normally manages blood sugar. When you eat carbohydrates, your body breaks them down into glucose, which enters your bloodstream. In response, your pancreas releases a hormone called insulin. You can think of insulin as a key; it unlocks your body's cells to allow glucose to enter and be used for energy.

In prediabetes, this process starts to fail. Your cells become less responsive to insulin’s signal – a condition known as insulin resistance. Your pancreas tries to compensate by producing even more insulin, but eventually, it can't keep up. As a result, glucose builds up in your bloodstream instead of being used by your cells, leading to elevated blood sugar levels.

Other names for prediabetes

Yes, the terms 'prediabetes', 'borderline diabetes', 'non-diabetic hyperglycaemia' and 'impaired glucose tolerance' are often used interchangeably to describe the same metabolic state.

As clinicians, we now prefer the term 'prediabetes'. It more accurately reflects the seriousness of the condition and highlights the very real risk of progression to full-blown type 2 diabetes if the condition is not actively managed. It emphasises that this is a crucial time for prevention.

Why prediabetes matters

Ignoring prediabetes can have serious long-term health consequences. Without intervention, many people with prediabetes will develop type 2 diabetes, often within five to ten years.

Furthermore, the long-term damage associated with diabetes – particularly to your heart and blood vessels – may already be starting during prediabetes. The condition itself increases your risk of heart disease and stroke, even if it never progresses to type 2 diabetes. Taking action is one of the most effective ways to protect your future health, as lifestyle changes are proven to prevent or delay type 2 diabetes for many people at high risk.

How prediabetes is diagnosed

Prediabetes is diagnosed using blood tests that measure your average blood sugar over time (HbA1c) or your blood sugar after fasting (Fasting Plasma Glucose). These tests give your doctor an objective measurement of how your body is managing glucose.

Key diagnostic tests

A GP will typically use one of two blood tests to screen for and diagnose prediabetes.

• HbA1c (glycated haemoglobin) test: This is the most common test used in the UK. It measures the amount of glucose that has attached to your red blood cells over the past two to three months, giving a reliable average blood sugar level. A major advantage is that you do not need to fast before the test.
• Fasting Plasma Glucose (FPG) test: This test measures your blood glucose at a single point in time after you have not eaten or drunk anything (except water) for at least eight hours.

UK HbA1c diagnostic ranges

In the UK, the HbA1c test is the standard for diagnosis. Your results are given in millimoles per mole (mmol/mol). According to NICE guidance, the ranges are as follows:

A result in the 42 to 47 mmol/mol range indicates that your blood sugar is higher than normal and you are at high risk of developing type 2 diabetes. NICE defines high risk as fasting plasma glucose of 5.5 to 6.9 mmol/L

US diagnostic ranges

You may sometimes see blood sugar results online from US-based sources, which use different units: milligrams per decilitre (mg/dL) for fasting glucose or a percentage (%) for HbA1c. For context, here are the approximate equivalents:

Questions to ask your doctor

Receiving a prediabetes diagnosis is the first step towards taking action. It's an opportunity to have a productive conversation with your GP. Consider asking:

• What do these numbers mean for my personal health risk?
• How often should I have my blood sugar re-tested to monitor my progress?
• Are there any other factors, like my blood pressure or cholesterol, that we also need to address?
• What local support or programmes, like the NHS Diabetes Prevention Programme, are available to me?

Prediabetes signs, symptoms, and risk factors

Most people with prediabetes have no clear symptoms, which is why understanding your risk factors is so important for early detection. The condition can develop slowly over several years without you noticing.

Why prediabetes is often asymptomatic

The gradual increase in blood sugar during the prediabetic stage is rarely dramatic enough to cause noticeable symptoms. This is why screening is so important, especially for those with known risk factors. When symptoms do appear, they are often subtle and can be easily mistaken for other things, like the general stresses of modern life. These early symptoms are often the first signs that your body is progressing towards type 2 diabetes.

Early signs and symptoms

If prediabetes starts to progress towards type 2 diabetes, you might begin to notice some early warning signs. The NHS lists several key symptoms that should prompt a conversation with your GP:

• Feeling very thirsty all the time
• Peeing more frequently than usual, particularly at night
• Feeling very tired
• Blurred vision
• Cuts or wounds that heal slowly

These symptoms can also be a sign of type 1 diabetes in adults but this is less common as type 1 usually presents in childhood.

Another specific physical sign can be the appearance of dark, velvety patches of skin, often on the neck, armpits or groin. This is a condition called Acanthosis nigricans and is a sign of insulin resistance.

Key prediabetes risk factors

Your risk of developing prediabetes is influenced by a combination of factors, some of which you can change and some you can't. You are at higher risk if you:

• Are over the age of 40. The risk increases as you get older.
• Are overweight or obese. Carrying excess weight, especially around your waist, is a major risk factor for insulin resistance.
• Have a close relative with type 2 diabetes. Your genetic makeup plays a significant role.
• Are of South Asian, African-Caribbean or Black African origin. These ethnic groups have a higher genetic risk.
• Have a history of gestational diabetes. If you had diabetes during pregnancy, your long-term risk is higher.
• Have high blood pressure. This often occurs alongside insulin resistance as part of the 'metabolic syndrome'. Speak to a clinician if you're concerned about high blood pressure.
• Live a sedentary lifestyle. A lack of physical activity contributes to insulin resistance.

A step-by-step plan for reversing prediabetes

Prediabetes can often be reversed through consistent lifestyle changes. In my clinical experience, patients who commit to a structured plan often achieve remarkable results. Structured lifestyle programmes focusing on diet, weight, and activity are proven to significantly reduce the risk of progression to type 2 diabetes, according to NICE. Your reversal plan is built on four key pillars.

Pillar 1: Improve nutrition

The goal is not to follow a highly restrictive 'diet', but to adopt a sustainable, balanced eating pattern that helps manage your blood sugar and improve your body’s sensitivity to insulin.

A simple and effective visual tool is the ‘Plate Method’. It helps you control portion sizes without complicated calorie counting. Aim to fill:

• Half your plate with non-starchy vegetables (like broccoli, leafy greens, peppers, and cauliflower).
• A quarter of your plate with lean protein (such as chicken, fish, beans, or tofu).
• A quarter of your plate with wholegrain or high-fibre carbohydrates (like brown rice, quinoa, wholewheat pasta, or sweet potato).

This approach is based on the principles of the NHS Eatwell Guide, which promotes a balanced diet for overall health.

Pillar 2: Increase physical activity

Physical activity is essential for reversing prediabetes. It makes your cells more sensitive to insulin, which means your body can use blood glucose more effectively. The UK Chief Medical Officers' guidelines recommend at least 150 minutes of moderate-intensity activity per week.

'Moderate intensity' means you should feel your heart rate increase and be breathing a little harder, but can still hold a conversation.

You can break this down into manageable chunks. For example:

• A brisk 30-minute walk, five days a week.
• A 45-minute bike ride or swim, three to four times a week.
• Two or three 10 to 15-minute walks spread throughout the day.

A particularly effective strategy is to take a short, 10-minute walk after your main meals. This can help lower the blood sugar spike that typically occurs after eating.

Pillar 3: Achieve a healthy weight

If you are carrying excess weight, losing even a modest amount can have a profound impact on reversing prediabetes. Research shows that losing just 5 to 7 per cent of your body weight can significantly improve insulin sensitivity and lower your HbA1c.

For a person weighing 100kg (approx. 15st 10lb), this means losing just 5 to 7kg (11 to 15lbs).

This weight loss is most effectively and sustainably achieved by combining the nutritional changes and increased physical activity described in the first two pillars. This is the cornerstone of any effective reversal programme. If you need support with this, a GP can discuss strategies for managing your weight in a healthy way.

Pillar 4: Manage stress and sleep

Your mental wellbeing and sleep patterns play a surprisingly important role in blood sugar regulation. These are often missing from basic advice but are critical for success.

• Stress: When you are under chronic stress, your body releases hormones like cortisol. Cortisol can raise blood sugar levels and make your body more insulin resistant over time.
• Sleep: A lack of quality sleep has a similar effect. Poor sleep disrupts the hormones that regulate appetite and blood sugar, making it harder to manage your weight and glucose levels.

Here are a few simple tips to help manage these factors:

• For stress: Try daily mindfulness or deep breathing exercises, even for just five minutes. Spending time in nature, like a walk in a park, is also proven to reduce cortisol levels.
• For sleep: Aim for a consistent seven to nine hours per night. Create a relaxing bedtime routine, avoid screens for an hour before bed, and make sure your bedroom is dark and quiet.

The timeline for prediabetes reversal

Reversing prediabetes is a gradual process that relies on consistency. The journey is different for everyone, depending on your starting point, your genetics, and how consistently you can implement lifestyle changes.

Tracking progress and setting goals

It’s important to understand that this is not an overnight fix. Instead of focusing solely on the number on the scales or your next blood test result, pay attention to non-scale victories first. These are the early signs that your new habits are working:

• Having more energy during the day.
• Noticing your clothes fit a little better.
• Feeling an improvement in your mood.
• Sleeping more soundly.

Tracking these positive changes can provide powerful motivation to keep going.

First 3 months: Building habits

This initial phase is all about establishing your new routines. The focus should be on consistency rather than perfection. Aim to build the habits of moving your body regularly and making healthier food choices meal by meal.

During this time, you may start to see some modest weight loss and feel better, but your HbA1c may not have changed significantly yet. The main goal here is to create a foundation of healthy habits that you can build on for the long term.

6-12 months: Seeing clinical results

This is typically the timeframe where consistent lifestyle changes translate into measurable clinical results. If you have stuck with your plan, it is very likely you will see a significant improvement in your HbA1c level when you have your follow-up blood test.

The ultimate goal is to bring your HbA1c back into the normal range, which is below 42 mmol/mol. A GP will arrange a repeat blood test to confirm your progress and advise on the next steps. Achieving this means you have successfully put prediabetes into remission. You will then still need a blood test to check this every year.

Conclusion

A diagnosis of prediabetes is a serious health warning, but it is also a powerful opportunity. It is a reversible condition, and you have the ability to change your future health trajectory.

The most important things to remember are that small, consistent lifestyle changes are powerful enough to make a real difference; a balanced diet, regular movement, and achieving a healthy weight are the pillars of reversal. Knowing your numbers through a simple blood test is the first step. Think of this diagnosis not as a setback, but as the motivation you need to build a healthier, more resilient future and prevent the long-term complications of type 2 diabetes.

If you are worried about your risk factors or have been diagnosed with prediabetes, discussing it with a GP can help you create a personalised plan. You can book a video appointment with one of our doctors at a time that suits you.