Prediabetes

Also called impaired fasting glucose or impaired glucose tolerance

Prediabetes is when the amount of glucose (sugar) in your blood is higher than normal. This means you are at much higher risk of getting type 2 diabetes and heart disease.

Key points

  1. Your body needs glucose from food and drinks for your cells to turn into energy. Insulin, which is made by your pancreas, manages this process. If you have too much body weight, this damages your pancreas, which leads to not enough insulin being produced or insulin not working properly. This leads to high blood glucose levels, or prediabetes.
  2. Symptoms of prediabetes include extreme thirst, urinating (peeing) more often and feeling tired.
  3. People who are overweight or obese, have a family history of type 2 diabetes or with Māori, Pacific or Indo-Asian ethnicity are at greater risk of developing diabetes.
  4. Finding out you have prediabetes can be an opportunity to make changes and stop it progressing to type 2 diabetes and increasing your risk of heart disease – prevention is better than cure.
  5. The best thing you can do to prevent or delay prediabetes progressing to diabetes is to maintain a healthy body weight, make healthy food and drink choices and take regular physical activity.

What is prediabetes?

Prediabetes occurs when the amount of glucose (sugar) in your blood is higher than normal. Insulin is the hormone that usually controls your blood sugars, keeping them in the healthy range. Sometimes people stop making enough insulin, or it does not work well enough, to control their blood glucose levels. This is called prediabetes.

People with prediabetes are at increased risk of developing type 2 diabetes and heart disease. However, if you follow a healthy lifestyle at this stage, you have a chance to delay or prevent the future development of type 2 diabetes.

What causes prediabetes?

People who are overweight or who have obesity are at higher risk of developing prediabetes. This is due to excess energy (from food and drinks) being stored as fat around your body’s organs and tissues. Over time, these fatty deposits can damage key organs, such as your pancreas, and lead to your body’s cells becoming less sensitive to insulin. This leads to your blood sugars rising, causing prediabetes.

How is prediabetes diagnosed?

Early signs of regular high blood sugar levels can include:

  • extreme thirst
  • needing to urinate often
  • dry skin
  • feeling hungry
  • blurred vision
  • feeling drowsy
  • wounds being slow to heal. 

If you have noticed some or all of these symptoms, visit your doctor for an HbA1c blood test. This test measures your average blood glucose over the previous 8 to 12 weeks and gives an indication of your longer-term blood glucose control. A result of 41 to 49 mmol/mol is considered to be prediabetes.

Who should be tested for prediabetes?

You may not notice any obvious symptoms of prediabetes, but if you are in any of the high-risk groups below, it’s important to talk to your doctor or nurse about a screening test.

If you are over 25 years of age and:

  • have obesity (BMI of 30 or more, or 27 or more if you are Indo-Asian)
  • have a family history of early age onset of type 2 diabetes in more than one first degree relative (parent, brother or sister)
  • are a woman who has had gestational diabetes
  • have cardiovascular disease (conditions affecting your heart and blood vessels)
  • are on long-term steroid or antipsychotic treatment.

If you are a child or young adult with obesity (BMI of 30 or more, or 27 or more if you are Indo-Asian) and:

  • there is a family history of early onset type 2 diabetes
  • you are of Māori, Pacific or Indo-Asian ethnicity (Indian, including Fijian Indian, Sri Lankan, Afghani, Bangladeshi, Nepalese, Pakistani, Tibetan).

It is a good idea for other adults to also be tested as you become due for a cardiovascular (heart health) risk assessment at age 35, 45 or 55.

How is prediabetes treated?

Prediabetes is treated by changing your lifestyle where needed. This could delay you developing diabetes by 3–4 years or even prevent you developing it. Healthy lifestyles are made up of healthy eating, active living, a healthy body weight and being smoke-free.

Healthy eating

  • Healthy eating is not about sticking to strict diets or depriving yourself of the foods you love. There is no special diabetes diet. Like everyone, you can follow Michael Pollan's advice to "Eat food. Not too much. Mostly plants."
  • Eat a wide range of different foods – mostly plant-based and less processed – that help you feel great, have more energy, improve your outlook and achieve or maintain a healthy weight.
  • Find out more about healthy eating basics.

Active living

  • Regular physical activity, sitting less and moving more can help you have a healthy body weight, feel more positive and lower your risk of diabetes, heart disease and some cancers.
  • Physical activity also helps your body to use insulin properly.
  • Aim to be active for at least 30 minutes every day, increasing to 60 minutes daily if you want to reduce your body weight.
  • Doing some physical activity is still better than doing none.
  • Find out more about physical activity.

A healthy body weight

  • If you have overweight or obesity, losing 5–10% of your initial body weight can significantly improve your blood sugars, blood pressure and cholesterol.
  • Making good choices about what you eat and drink, and being physically active, are important to achieve and keep a healthy body weight.
  • For every one kilogram of weight you lose, your risk of diabetes could reduce by 16%.

Be smoke-free

If you are a smoker, quitting smoking is also important.

Medication

If lifestyle changes don’t lead to your blood glucose levels reducing enough, your doctor may consider also prescribing metformin

Support

Diabetes support groups
Diabetes self-management support (6–8 hours over 1 day or for 3–4 consecutive weeks) is available in some areas. Ask your GP or practice nurse what’s available in your area.

Learn more

The following links provide further information about prediabetes. Be aware that websites from other countries may have information that differs from New Zealand recommendations. 

More tips for preventing type 2 diabetes 
Pre-diabetes Diabetes NZ Auckland Branch
JumpStart Exercise, nutrition and support programme for people with diabetes and prediabetes
Diabetes New Zealand

References

  1. Prediabetes – risk factor management  Ministry of Health, NZ, 2016
  2. HbA1c testing

Reviewed by

Julie Carter works as a liaison dietitian for the Auckland District Health Board. She has an interest in public health nutrition.
Credits: Health Navigator Editorial Team. Reviewed By: ADHB community liaison dietitian Julie Carter Last reviewed: 01 May 2018