What is prediabetes and what can be done about it?

Written by: Dr David Cavan
Edited by: Bronwen Griffiths

Prediabetes is a condition where the level of sugar (glucose) in the blood is higher than normal, but not yet high enough to diagnose diabetes. It usually, but not always, occurs in people who are overweight and have a sedentary lifestyle. People with prediabetes are at high risk of progressing to develop type 2 diabetes. Dr David Cavan is a leading endocrinologist and author of Reverse Your Diabetes: The Step-by-Step Plan to Take Control of Type 2 Diabetes, and here he explains what prediabetes is and how it can be reversed.

What blood glucose level is prediabetic?

Prediabetes is diagnosed if the fasting blood glucose level is between 6.1 and 7.0 mmol/l. It is also diagnosed by an HbA1c blood test, which provides an overview of glucose levels over the previous 6 to 8 weeks. A level between 42 and 47 mmol/mol (6.0 to 6.4%) is diagnostic. Once levels increase above this, then the person is diagnosed as having type 2 diabetes.

What are the signs of prediabetes?

There are no specific signs or symptoms of prediabetes, although often it can be associated with being overweight, having high blood pressure and a high cholesterol level.

Can you reverse prediabetes?

Yes! It used to be thought that if you had prediabetes, then you would likely end up having type 2 diabetes and there was nothing you could do to stop that happening. Then around 15 years ago, large-scale research studies in Finland and the US demonstrated that if people with prediabetes adopt a healthier lifestyle, then they can reduce the risk of developing type 2 diabetes. Those studies also showed that in some cases, glucose levels returned to normal. Since then, many people have been able to reverse from prediabetes to normal glucose control.

What should you eat if you are prediabetic?

To my mind, the goal of treatment for anyone with prediabetes is to try and reverse the condition, and dietary changes are the most effective. In my experience, this is best achieved by cutting out sugar as much as possible and also reducing starchy carbohydrates to a minimum. That means avoiding bread, cakes, biscuits, potatoes, pasta, rice and breakfast cereals. In their place, I encourage increased intake of fresh leafy vegetables, healthy fats which are found in nuts, olives, avocadoes and unsweetened dairy products, and good quality sources of protein such as meat, fish, eggs or pulses.


If you are concerned about being prediabetic, make an appointment with an expert.

By Dr David Cavan
Endocrinology, diabetes & metabolism

Dr David Cavan is one of the UK's leading diabetes physicians with considerable experience and expertise in all aspects of the management of the condition. He has particular interest in the intensive management of type 1 diabetes including insulin pump therapy, and lifestyle management in those with type 2 diabetes.

Dr Cavan strongly believes in the importance education and self-management for people with diabetes, and he has developed educational programmes for those with type 1 & 2 diabetes. He has worked on a number of global projects, including most recently the development of programmes in Bermuda to tackle the high prevalence of type 2 diabetes there. 

Dr Cavan has contributed to numerous peer-reviewed publications on many aspects of diabetes. In 2014, he published his first book, 'Reverse your diabetes: the step by step plan to take control of type 2 diabetes'. This was followed in 2016 by 'Reverse your diabetes diet'. In 2018 he published two books, 'Take control of type 1 diabetes' and, together with food writer Emma Porter, 'The low carb diabetes cookbook'.   

He consults at London Medical on Wednesday afternoons.  Please call to book an appointment.  Alternatively, he is available for e-consultations via Topdoctors. Please note that the private messaging function is not suitable for detailed advice and should only be used as a follow up to a face to face or e-consultation.

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