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The Prediabetes Nutritionist

Prediabetes - What You Need to Know

Prediabetes: What You Need to Know

Prediabetes is considered a high-risk state for diabetes and cardiovascular disease. This blog post discusses prediabetes, factors that increase risk and how to prevent it.

Prediabetes is when your blood sugar levels are higher than normal but not high enough to be considered diabetes. However, it increases the risk of developing diabetes, heart disease, or stroke.1

In prediabetes, your muscles, liver, and fat cells cannot respond to insulin appropriately, which makes it difficult for them to take up glucose from the bloodstream; this condition is called insulin resistance.1 The pancreas produces more insulin to compensate for this; initially, blood sugar levels remain normal. But over time, the pancreas cannot keep up, and blood glucose gradually rises above normal.1

How many people does prediabetes affect globally?

There are two types of prediabetes – impaired glucose tolerance (IGT) and impaired fasting glucose (IFG). According to the International Diabetes Federation, an estimated 541 million adults worldwide have IGT, while 319 million have IFG.2 The IGT figures are expected to increase to 730 million adults and IFG to 441 million adults by 2045.2 Also, over 80% of adults with prediabetes in the U.S. are unaware they have it.3,4 Scientists estimate that 5-10% of people with prediabetes develop diabetes, while a similar percentage return to normal blood glucose levels.1,4

Prediabetes Statistics in Adults (20-79 Years) in IDF Regions.2
 Impaired Glucose Tolerance (IGT) (millions)Impaired Fasting Glucose (IFG) (millions)
IDF Region2021204520212045
Western Pacific253291.84762.8
North America and the Caribbean4756.631.637.6
Middle East and North Africa47.680.540.984.7
South and Central America39.652.728.947.5
Southeast Asia46.976.649.756.0

Who is more likely to develop prediabetes?

People with certain genetic and lifestyle risk factors are more likely to develop prediabetes. Some of these risk factors include:5,6,7

  • Age >40 in Caucasians or over 25 in African-Caribbean, Black African, Chinese or South Asian)
  • Overweight (BMI ≥ 25 kg/m2 in Caucasians or ≥23 kg/m2 in Asians)
  • High waist circumference
  • Having a first-degree relative (parent, sibling or child) with diabetes
  • Being from the Pacific Island or of African American, Latino, Native American, or Asian American descent
  • History of cardiovascular disease
  • High blood pressure (≥ 130/80 mmHg or taking blood pressure medication)
  • Low HDL ‘good’ cholesterol (< 35 mg/dL [0.9 mmol/L) and/or high triglycerides >250 mg/dL (2.82 mmol/L)
  • Polycystic ovary syndrome
  • Physical inactivity
  • Having conditions associated with insulin resistance (severe obesity, acanthosis nigricans)
  • History of diabetes during pregnancy (gestational diabetes)
  • Smoker
  • Mental health conditions

What causes prediabetes?

Scientists are still uncertain about the cause prediabetes, but evidence suggests that unhealthy diets, lack of exercise, and carrying excess fat around the abdomen contribute to its development.

A Caucasian woman with a waist circumference of 80cm (31 inches) or more has a high risk of insulin resistance. Similarly, a Caucasian man with a waist circumference of 96cm (38 inches) or more has a high risk. Women with waist circumference greater than 88cm (35 inches) and men with waist circumferences greater than 102cm (40 inches) have an even higher risk.8

Waist Circumference4Threshold value
Higher risk cut-offMenWomen
Canada, United States≥102cm (≥40 inches)≥88cm (≥35 inches)
Middle Eastern, sub-Saharan African, Mediterranean≥94cm (≥37 inches)≥80cm (≥31 inches)
Asian, Japanese, South and Central American≥90cm (≥35.4 inches)≥80cm (≥31 inches)
Chinese≥80cm (≥31 inches)≥80cm (≥31 inches)

What are the symptoms of prediabetes?

Prediabetes does not usually have symptoms. However, if you experience the following symptoms, you have likely developed type 2 diabetes. In such cases, scheduling a blood test with your doctor is vital, especially if you have risk factors.

Some of the symptoms associated with type 2 diabetes include:

  • Feeling extremely thirsty with a dry mouth
  • Urinating frequently, especially at night
  • Feeling fatigued
  • Slow healing wounds
  • Frequent skin infections
  • Blurred vision
  • Tingling or numbness in hands and feet

How do doctors test and diagnose prediabetes?

Doctors can diagnose prediabetes with different tests. These are:5

  1. A fasting blood glucose test, which measures blood glucose levels after an overnight (at least 8 hours) fast.
  2. The oral glucose tolerance test (OGTT), which measures blood glucose two hours after drinking a fluid containing 75g of glucose. This test checks how well your body handles sugar.
  3. The glycated haemoglobin (HbA1c) test, which measures the average blood sugar over the past two to three months. This test measures the amount of sugar attached to your red blood cells.

People with prediabetes can have impaired fasting blood glucose, impaired glucose tolerance, or both. It is worth noting that people with impaired glucose tolerance are more likely to develop diabetes and cardiovascular disease.

Your doctor will diagnose prediabetes if your:

  • Fasting blood glucose is 5.6-6.9 mmol/L (100-125 mg/dL) in the U.S. and 6.1-6.9 mmol/L (110-125 mg/dL) in the U.K.
  • OGTT is 7.8-11.0 mmol/L (140-199 mg/dL)
  • HbA1c is 5.7-6.4% (39-47 mmol/L) in the U.S. and 6.0-6.4% (42-47 mmol/L) in the UK
Diagnosis of Prediabetes
TESTThe U.S.The U.K.
Fasting blood glucose5.6-6.9 mmol/L (100-125 mg/dL)6.1-6.9 mmol/L (110-125 mg/dL)
Oral glucose tolerance test7.8-11.0 mmol/L (140-199 mg/dL)7.8-11.0 mmol/L (140-199 mg/dL)
HbA1c5.7-6.4% (39-47 mmol/L)6.0-6.4 (42-47 mmol/L)

How can I prevent or reverse prediabetes?

Eating a healthy diet, increasing activity and weight loss is the best way to prevent insulin resistance and prediabetes.5 A healthy diet contains fruits, vegetables, nuts, seeds, legumes, starchy carbohydrates and wholegrains. Eating adequate portions and limiting the intake of foods high in sugar, salt and saturated fat, such as chocolate, sweets, pastries, crisps, ice cream and desserts, is also essential.9

Aim for at least 150 minutes of weekly activity, including aerobic exercise such as brisk walking, running, jogging, HIIT training or cycling and strength-training exercises, such as weight-lifting and callisthenics.5 In clinical studies, exercise improves insulin sensitivity and supports weight loss.5

If you have overweight or obesity, aim to lose at least 7% of your body weight.5 This level of weight loss reduced the onset of type 2 diabetes by 58% in clinical studies. 5


  1. Tabák, A. G., Herder, C., Rathmann, W., Brunner, E. J., & Kivimäki, M. (2012). Prediabetes: A high-risk state for developing diabetes. Lancet, 379(9833), 2279.
  2. International Diabetes Federation. IDF Diabetes Atlas, 10th edn. Brussels, Belgium: 2021. Available at:
  3. Centres for Disease Control and Prevention (2022) Prediabetes – Your chance to prevent type 2 diabetes. Available: Last accessed: 06 October 2023.
  4. Twohig, H., Hodges, V., & Mitchell, C. (2018) Pre-diabetes: opportunity or overdiagnosis? British Journal of General Practice, 68 (669): 172-173.
  5. ElSayed, N.A., Aleppo, G., Aroda, V.R., Bannuru, R.R., Brown, F.M, et al., (2022) Classification and diagnosis of diabetes: Standards of Care in Diabetes – 2023. Diabetes Care, 46 (Supplement_1): S19-S40.
  6. Tuso, P. (2014) Prediabetes and lifestyle modification: Time to prevent a preventable disease. The Permanente Journal, 18(3): 88-93.
  7. Alvarez, S., Coffey, R., Algotar, A.M (2023) Prediabetes. Available: Last accessed: 06 October 2023
  8. Ross, R., Neeland, I.J., Yamashita, S., Shai, I., Seidell, J., Magni, P., Santos, R.D., Arsenault, B., Cuevas, A., Hu, F.B., Griffin, B.A., Zambon, A., Barter, P., Fruchart, J-C., Eckle, R.H., Matsuzawa, Y., & Despres, J-P. (2020) Waist circumference as a vital sign in clinical practice: a Consensus Statement from the IAS and ICCR Working Group on Visceral Obesity. Natura Reviews Endocrinology, 16, 177-189.
  9. Von Frankenberg, A. D., Marina, A., Song, X., Callahan, H.S., Kratz, M., & Utzscheider, K.M. (2017) A high-fat, high-saturated fat diet decreases insulin sensitivity without changing intra-abdominal fat in weight-stable overweight and obese adults.  European Journal of Nutrition, 56(1): 431-443.

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