What is prediabetes?

Prediabetes, sometimes called borderline diabetes, is an indication that you are at a high risk of developing type 2 diabetes. This is because your blood sugar levels are above the normal range. 

How is prediabetes different from diabetes?

If you are diagnosed with prediabetes it means your blood sugar levels are higher than normal, but not high enough for type 2 diabetes. You may not experience any diabetic-like symptoms if you have prediabetes, so it may be diagnosed using a specific blood test called HbA1c. Prediabetes increases your risk of stroke, heart disease, and type 2 diabetes, but it may be reversible with changes to your lifestyle. 

What are the symptoms of prediabetes?

Prediabetes doesn’t have any symptoms, so if you are experiencing type 2 diabetes symptoms, it’s likely you have already developed it.

It is important to spot diabetes early, so that it can be treated appropriately. The symptoms of type 2 diabetes include:

• needing to pee more often, especially during the night
• feeling very thirsty
• feeling very tired
• blurred vision
• wounds and cuts taking longer to heal
• weight loss
• itching around the genitals or thrush

What are the warning signs of prediabetes?

Because prediabetes doesn’t have any symptoms, it can be difficult to spot, but there are certain factors that could increase your risk. These include:

• your ethnicity - you’re at a higher risk if you are white and over 40 or African-Caribbean, Black African, or South Asian and over 25
• your family history - if a parent, sibling, or child has diabetes, your risk will increase
• you have high blood pressure
• you’re overweight, especially if you carry extra weight around your middle

Prediabetes complications

Undiagnosed or untreated prediabetes can lead to complications, and the disease may be causing damage to your body without you realising. Understanding your risk and getting diagnosed early will help to limit the damage prediabetes causes your body. 

Long-lasting effects of prediabetes

If prediabetes is left untreated, it can lead to type 2 diabetes and other health conditions, such as:

• heart disease
• stroke
• kidney damage
• nerve damage
• sight problems
• hearing loss
• skin infections
• problems with the blood supply or sensation in your feet

How long does it take for prediabetes to turn to diabetes?

It is estimated that without treatment, prediabetes can turn into type 2 diabetes within 5 years. Some research shows that up to 10% of people with prediabetes become diabetic every year.

What causes prediabetes?

Prediabetes is caused by your body struggling to process the food you eat. Your body naturally produces insulin to help break down sugar (glucose) and distribute it into your cells. When your body stops producing enough insulin, or your cells stop responding as well to insulin, this can cause prediabetes. 

What increases your risk of prediabetes?

Factors that can increase your risk of prediabetes include:

• being overweight or inactive
• having high blood pressure
• a family history of type 2 diabetes
• your ethnicity
• smoking
• drinking above the recommended alcohol limits

How do I know if I have prediabetes?

There are no symptoms associated with prediabetes, that is why it is essential to get tested, especially if you are at an increased risk. 

How do I test for prediabetes?

The main test used by healthcare professionals to diagnose prediabetes and diabetes is the HbA1c test. In the blood, some glucose attaches to the protein responsible for carrying oxygen around your body, called haemoglobin. The combination of haemoglobin and glucose is called HbA1c and is directly linked to the average amount of glucose in the blood.

Because red blood cells can survive for 2 to 3 months, a HbA1c can tell you your average blood glucose level during the previous 8 to 12 weeks. If your HbA1c levels are high, it can indicate prediabetes or uncontrolled diabetes. An HbA1c may not be suitable for some people such as if you are currently or have recently been pregnant in which case your doctor or midwife will use a different test to check for pre-diabetes. 

What is the prediabetes blood glucose level range?

The World Health Organisation suggests the following HbA1c ranges for diagnosing diabetes:

• below 42 mmol/mol means no diabetes
• between 42 and 47 mmol/mol is indicative of prediabetes
• over 48 mmol/mol suggests you have type 2 diabetes.

What should I do if I have prediabetes? 

If you are diagnosed with prediabetes you will be advised to speak to your doctor. They will advise you about how to manage the condition with lifestyle changes like diet and exercise.

You’ll also be advised to regularly test your average blood glucose levels using a blood glucose monitor, as well as regular HbA1c tests to monitor your average blood glucose levels.

Is prediabetes reversible?

Prediabetes is recognised as a reversible condition. Research shows that prediabetes can be prevented from turning into diabetes for as long as 10 years through lifestyle interventions. 

How to reverse prediabetes

There are two main ways that prediabetes can be reversed; with medication, and through lifestyle changes such as diet and exercise. 

Prediabetes medication

Metformin may be prescribed to treat prediabetes and stop it from developing into type 2 diabetes. Metformin is a first-line treatment in diabetes and helps to lower blood sugar levels by improving the way the body uses insulin. 

Medication shouldn’t be the first line of treatment for prediabetes though. Lifestyle interventions like improving your diet and getting active can be very effective at preventing prediabetes from becoming type 2 diabetes.

How to reverse prediabetes naturally

There are steps you can take to help reverse diabetes naturally, such as changing your diet and increasing your activity levels. Leading a sedentary (inactive) lifestyle is a risk factor for developing type 2 diabetes. So, increasing your activity levels can help to reduce your risk. 

You don’t need to invest lots of money in gym memberships or specialist equipment. You can just make small changes every day, such as walking to work instead of driving, using the stairs instead of a lift or escalator, or even doing some gardening or housework.

Exercise helps to increase the body’s sensitivity to insulin and, in combination with a healthy diet, can lessen the body’s demand for the hormone. In turn this can help to reverse diabetes. There’s no specific diet that you should follow if you are at an increased risk of type 2 diabetes. Instead, it’s about balance and eating the right foods.

For example, foods that are high in fat and low in fibre are linked to the development of diabetes. So, it’s important to make healthy swaps and follow a diet that consists of healthier choices such as fruit, vegetables, whole grains, and lean meats and proteins. 

Is there a prediabetes diet?

No, there is no specific diet you should follow if you have prediabetes. There are certain dietary patterns which have been shown to reduce your risk of type 2 diabetes. They are:

• The Mediterranean Diet - a diet based on the cuisines of countries that border the Mediterranean sea. Traditionally, the diet is high in fruit, vegetables, wholegrains, nuts, pulses, seeds, moderately high in seafood and oily fish and low in dairy and red meat.
• Dietary Approaches to Stop Hypertension (DASH) diet -  a low salt diet that’s rich in fruit, vegetables, wholegrains, fish, poultry, and nuts but limits the intake of foods that are high in saturated fats, like full-fat dairy products and fatty meats.
• The Nordic diet - the Nordic diet is similar to the Mediterranean Diet but incorporates the foods eaten by Nordic people. It is high in fruit, vegetable, whole grains, seafood, low fat dairy, and plant oils but low in red meat and animal fat. 
• Vegan and vegetarian diets - vegan and vegetarian diets are rich in fruits, vegetables and wholegrains and omit the intake of all meats and animal products (in the case of vegan diets).

The major benefit of these diets is they all have a low intake of high fat and processed foods. Instead, they are mostly made up of natural, plant-based foods and are high in fibre and low in fat. 

What should I eat with prediabetes?

If you have prediabetes, there are certain foods and food groups you should try to eat. They are:

• fruit and vegetables like green leafy veg (spinach, kale, chard, and collard greens),  apples, blueberries
• wholegrains (oats, rice quinoa, barley and rye)
• low-fat dairy products such as yoghurt and cheese
• oily fish like salmon, mackerel, sardines, and herring. You should aim to eat 2 portions of oily fish per week

What shouldn’t I eat if I have prediabetes?

If you have prediabetes, there are certain foods you should avoid or limit your intake of because they can contribute to your risk of developing type 2 diabetes. They are:

• sugary drinks such as cola or energy drinks
• red and processed meats (beef, lamb, burgers, sausages, bacon, kebab meat)
• refined carbohydrates like white bread, pasta, rice, sugary snacks (sweets, cakes, biscuits), and sugary cereals
• potatoes 

There are some healthy swaps you can make to help keep your diet balanced, varied and healthy, such as swapping:

• sugary cereals in the morning for porridge oats with blueberries or poached or boiled egg with wholegrain toast
• biscuits for a handful of nuts and seeds
• sugary drinks for fresh water
• white pasta for wholewheat or brown varieties
• full-fat milk for skimmed or plant varieties such as unsweetened oat, almond, or soya
• potatoes for sweet potatoes

Sources

About prediabetes and type 2 diabetes (2021) CDC [accessed 11 July 2022]

Diabetes (2019) NHS [accessed 11 July 2022] 

Diabetes tests (2022) Diabetes UK [accessed 11 July 2022]

HbA1c test (2021) Lab Tests Online [accessed 11 July 2022]

Medications for prediabetes (2022) Drugs.com [accessed 11 July 2022]

Metformin (2022) NHS [accessed 11 July 2022]

Prediabetes: A high-risk state for developing diabetes (2014) Lancet [accessed 11 July 2022]

Prediabetes and lifestyle modifications (2014) Perm J [accessed 11 July 2022] 

Treating prediabetes with metformin (2009) CFP MFC [accessed 11 July 2022]