What is pre-diabetes?
Pre-diabetesBlood SugarGeneral Health

What is pre-diabetes?

What is pre-diabetes?

January 27, 2021

Here's the lowdown on pre-diabetes; its causes, symptoms and changes you can make to help reverse it.

What is pre-diabetes?

Pre-diabetes occurs when your blood sugar levels are higher than normal but below the threshold for diabetes. It is estimated that nearly 4 million people in the UK have diabetes and this number is rapidly increasing every year. If pre-diabetes is left undiagnosed and untreated after a period of time, type 2 diabetes develops.

Type 2 diabetes is caused by the level of sugar (glucose) in the blood becoming too high. Over time, this results in the body being unable to produce the amount of insulin needed, or your body resists the effects of insulin. Those who develop type 2 diabetes almost always have pre-diabetes first without displaying symptoms at the time.

Prediabetes Blood test

There are three types of blood tests that can be carried out that helps identify and diagnose prediabetes.

Haemoglobin A1c Test

An HbA1c test provides a longer term trend of your blood sugar levels. Measuring this protein within your red blood cells gives an overall picture of your sugar levels. As the lifetime of a red blood cell is about 8 to 12 weeks this test provides an indication of average blood glucose levels throughout this time.

  • Normal HbA1c levels are at below 6% (below 42 mmol/mol)

  • Pre-diabetes 6.0 to 6.4% (42 to 47 mmol/mol)

  • Diabetic levels are 6.5% and over (48mmol/mol or over)

Fasting Plasma Glucose (FPG)

This test works by measuring glucose levels after a period of fasting. This test measures your current glucose levels. Following a period of 8 hours (usually overnight) without eating, one of our trained professionals will take a sample of blood. A high level of glucose after fasting can be a sign of pre-diabetes and expose problems with how the body is producing insulin.

Normal FPG tests levels 70mg/dL to 99mg/dL

Pre-diabetes 100mg/dL to 126mg/dL

Diabetic levels are over 126mg/dL

If a high FPG test result is high or abnormal, it is often necessary to repeat the test or combine it with another test to confirm if you have prediabetes.

Oral Glucose Tolerance Test (oGTT)

This is a test used to investigate if you have prediabetes or diabetes, by seeing how your body responds to a dose of glucose. You will be asked not to eat and drink only water for 8 to 12 hours before the test is carried out (usually overnight). It involves measuring your blood glucose levels after drinking a sweet, sugary drink quickly (within 5 minutes). A sample of blood will then be taken and analysed in the lab where your results show if your glucose levels are well controlled. Additional blood samples will be taken at regular intervals up to 2 hours. Results are reported in mmol/L.

At Melio, we don’t offer oGTT testing.

Normal test levels

  • Fasting sample: Less than 6.0

  • 2 hour sample: Less than 7.8

Pre-diabetes test levels

  • Fasting sample: Between 6.0 and 7.0

  • 2 hour sample: Between 7.8 and 11.0

Diabetic test levels

  • Greater than or equal to 7.0

  • Between 7.8 and 11.0

What causes pre-diabetes?

The presence of pre-diabetes increases the risk of developing type 2 diabetes from 3 times to 10 times more likely. Identifying pre-diabetes is essential in preventing type 2 diabetes.

Causes and risk factors of pre-diabetes include:

  • Age, you are more likely to develop pre-diabetes if you are over 45 although prediabetes can occur at any age.

  • Waist size, a waist size greater than 40 inches for men and 35 inches for women in impact insulin resistance

  • Being overweight is a primary risk for pre-diabetes, more fat located around the abdomen causes resistance of cells to insulin.

  • Having high cholesterol

  • Having sleep problems such as sleep apnoea

  • Blood pressure levels

  • Being of south Asian ethnicity

  • Gestational diabetes (when a woman develops high blood sugar during pregnancy)

  • Women with polycystic ovary syndrome are at higher risk of developing prediabetes

  • High calorie diets

  • Smoking

  • Lack of physical activity

  • Family history of diabetes

Pre-diabetes complications

Along with the risk of developing type 2 diabetes, prediabetes can cause microvascular arterial disease which can lead to heart or peripheral vascular disease.

Macrovascular disease can also develop and damage large blood vessels leading to conditions such as TIA or stroke.

Developing diabetes can cause kidney failure, blindness, nerve damage (which can lead to amputation) and it can make you at high risk of having a stroke.

Pre-diabetes symptoms

Pre-diabetes may not show any symptoms at all and can develop over several years unnoticed. Symptoms can be hard to spot but include:

  • Being a lot thirstier than usual.

  • Needing to pee often

  • Blurred vision

  • Fatigue or feeling more tired than usual

Lifestyle and pre-diabetes

Detecting pre-diabetes is a crucial step in stopping the development of type 2 diabetes. Prediabetes can be reversed with healthier lifestyle changes:

  • Losing excess weight

  • Getting more exercise

  • Reducing high calorie foods

  • Reducing sugary food intake

  • Keeping blood pressure at a healthy level

Being diagnosed with prediabetes is a red flag but improved lifestyle choices can dramatically improve your health and risk of developing prediabetes.

Check your health status today

If you think you might be at risk of developing diabetes or pre-diabetes, it's easy to get tested with Melio. Our General Health Check and Cardiovascular Risk tests will check your blood sugar levels, and give you an overview of your personal health. Find out more about the General Health Check and Cardiovascular Risk tests here, and book your test today.


Edwards, Catherine M, and Kenneth Cusi. Prediabetes: A Worldwide Epidemic. Endocrinology and metabolism clinics of North America vol. 45,4 (2016): 751-764. doi:10.1016/j.ecl.2016.06.007



Wilson, Mara Lynn. Prediabetes: Beyond the Borderline. The Nursing clinics of North America vol. 52,4 (2017): 665-677. doi:10.1016/j.cnur.2017.07.011

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