What it is
Prediabetes is blood glucose raised above the normal range, but not yet at the level of type 2 diabetes. You may also hear it called non-diabetic hyperglycaemia, impaired fasting glucose, or impaired glucose tolerance, depending on which test found it.
Symptoms to look out for
Raised blood sugar in prediabetes usually causes no symptoms. The insulin resistance behind it can show up as:
- A larger waist, and difficulty losing weight
- Low energy and tiredness
- Sometimes low mood
- Raised blood pressure
- Darker skin on the neck, armpits and groin, and skin tags
Diagnosis is by blood test, most often HbA1c. In the UK the prediabetes range is 42–47 mmol/mol (6.0–6.4%).
Who is at risk
Excess weight around the middle, low muscle mass, inactivity, a diet high in sugar and ultra-processed food, increasing age, poor sleep, and longer-term stress. Family history of type 2 diabetes. Past gestational diabetes or PMOS (previously called PCOS). Risk is also higher in South Asian, African and African-Caribbean backgrounds.
Often reversible, and worth acting on early
By the time blood sugar reaches the prediabetes range, insulin resistance has usually been building for several years, often alongside a larger waist and fat in the liver. Because it is largely driven by lifestyle, it responds well to lifestyle change, often within weeks to a few months. Many people can return their blood sugar to normal.
What you can do
- Food. Reduce sugar, sugary drinks, refined carbohydrate and ultra-processed food. Build meals around good sized portions of protein, enjoy non-starchy vegetables, and add natural fats if desired. Some people find keeping total carbohydrate under about 130g a day is enough, while others do better lower still.
- Movement. Aim for at least 150 minutes of moderate activity a week, and a walk after meals is particularly useful. Add 2 to 3 resistance sessions a week to build muscle, which takes up glucose.
- Sleep and stress. Aim for 7 to 9 hours of regular sleep, as poor sleep worsens insulin resistance. Reduce long-term stress where you can.
- Keep track. You can monitor your blood glucose with sensors. Re-check your HbA1c three months after making changes.
Medicines and supplements
Metformin is sometimes considered, though it is not licensed for prediabetes in the UK. The right lifestyle changes are usually effective enough. A vitamin D3 and magnesium supplement may be useful. Discuss any supplement with a pharmacist or clinician.
When to get help
- If you have been told you have prediabetes, arrange follow-up to agree a plan and a monitoring schedule (usually annually).
- Have an annual check for prediabetes if you are at higher risk of developing it.
- See a doctor promptly if you develop excessive thirst, passing a lot of urine, unexplained weight loss, persistent fatigue or blurred vision.