Prediabetes: Causes, Symptoms and Complications

At a glance:

  • Prediabetes is a condition in which a person’s blood glucose levels are higher than normal but not high enough for a diagnosis of type 2 diabetes.
  • Around 2 million Australians have prediabetes and around one third will develop type 2 diabetes as a result.
  • A number of factors may increase your risk of developing prediabetes, including excess weight, age, genetics, ethnicity, smoking, lack of exercise and an unhealthy diet.
  • Prediabetes may be managed through lifestyle changes, significantly reducing the risk that it will develop into type 2 diabetes.

What is Prediabetes?

Prediabetes describes the condition of a person having blood sugar levels that are higher than normal but not high enough for a diagnosis of type 2 diabetes . Rather than being a disease or condition in itself, prediabetes is a risk factor that greatly increases a person’s chance of developing type 2 diabetes as well as cardiovascular conditions including heart disease and stroke.

According to Diabetes Australia , around two million Australians have prediabetes and approximately one third will develop type 2 diabetes.

Symptoms of Prediabetes

Prediabetes is asymptomatic, making it hard to detect. The only way to find out if you have prediabetes is to have your blood glucose levels tested . This requires a fasting glucose test and HBA1C. An oral glucose tolerance test is an outdated test that doesn’t offer any value over these two, simple easy to measure parameters. 

This test requires the patient to fast for around 8-10 hours beforehand. This is a simple guide to these fasting results.

  • Blood glucose- Normal 3.5-5 mmol/L; Prediabetes 6-7.5 mmol/L; Diabetes > 7.5 mmol/L
  • HBA1C- Normal < 5.5%; Pre-diabetes 5.5-6.5%; Diabetes >6.5%

Please note, the HBA1C is the best, simple indication of 3 month glucose control.

If you’re over 45 or carry extra weight around the middle, it may be time to book an appointment to see a doctor for a blood glucose test.

What Causes Prediabetes?

There are a number of risk factors that contribute to the development of pre-diabetes, including:

  1. Weight - Being overweight or obese increases your chance of developing prediabetes thanks in part to fat cells causing your body to become more insulin resistant. Even though it’s not the most accurate measure because it doesn’t take into account race, sex or muscle mass, a BMI of 25 or over is considered a risk factor for prediabetes.
  2. Waist Measurement - Carrying extra weight around the middle is a more accurate measure of weight issues than BMI. Having a waist measurement larger than 94cm in men or 80cm in women may be a risk factor for prediabetes.
  3. Lifestyle Factors - A lack of physical activity may be a contributing factor to weight issues but it is also a risk factor in itself. Eating a poorly balanced diet, frequently skipping meals and binge eating may also contribute to problems with insulin production and prediabetes.
  4. Age - Anyone may develop prediabetes but chances increase after the age of 45. At 65, the chance for developing prediabetes increases exponentially.
  5. Genetics - Insulin resistance is the major genetic factor in the development of prediabetes & type 2 diabetes. 30% of Caucasians, 50% of Asians & close to 100% of people with darker skin are insulin resistant. A family history of type 2 diabetes or heart disease are both risk factors. In addition, a number of ethnic groups have an elevated chance of developing prediabetes. These groups include; Aboriginal and Torres Strait Islander people, and people with Middle Eastern, South Asian, Pacific Islander or North African descent. 
  6. Smoking - Smoking has been linked to increased insulin resistance and may also lead to carrying more weight around the middle. 
  7. Certain Medications - A number of medications may increase your chance of developing prediabetes, such as Corticosteroids, Thiazide diuretics and Beta-blockers (high blood pressure drugs), some antipsychotic medications and statins (for cholesterol).
  8. High Blood Pressure
  9. Cholesterol - High triglycerides combined with low HDL-C (good cholesterol). 
  10. Gestational Diabetes - Women who have experienced gestational diabetes have a higher risk of developing prediabetes after pregnancy. Even without gestational diabetes, women who have given birth to a child with a heavy birth weight (4.5kg) also have an elevated risk of developing prediabetes.
  11. Polycystic Ovary Syndrome (PCOS) - Insulin resistance is a major factor in the development of PCOS. If you have polycystic ovary syndrome it is highly likely you are insulin resistant and therefore at risk of prediabetes. 

Complications of Prediabetes

Having prediabetes doesn’t mean you are guaranteed to develop type 2 diabetes but you do have a much higher risk than a person with an average blood glucose level. People with prediabetes are between 10 and 20 times more likely to develop type 2 diabetes than the general population.

Studies have shown that pre-diabetes not only increases the chances of developing cardiovascular conditions, it may also increase the rate of mortality for these conditions.

Managing Prediabetes

The good news is that pre-diabetes may be managed with lifestyle change, reducing the chance of any complications or the development of type 2 diabetes.

Weight Loss
If you are overweight or obese, losing between 5% and 10% of your body weight may significantly reduce your chances of developing type 2 diabetes.

Regular exercise is not only essential for a healthy body and to lose weight, it may also help in a number of other ways. When you exercise your body uses glucose for energy. In addition to lowering your blood glucose, exercise may make it easier for your body to metabolise glucose, reducing your insulin resistance.

Eating a healthy, balanced diet may help you lose weight as well as keep your blood glucose levels in an acceptable range. A dietician or Credentialed Diabetes Educator (CDE) may work with you to create a diet plan that fits in with your lifestyle, favourite foods and cultural preferences. 

In general, a diet high in fruits, vegetables and high fibre foods, high quality fats and avoiding sugars & other processed carbohydrates is advised.

Quit Smoking
Smoking may increase insulin resistance. Smoking raises your risk of developing type 2 diabetes by around 40%. 

Get Yearly Prediabetes Checks
If you have been diagnosed with prediabetes it is essential to have regular blood glucose tests to monitor the progress of the condition to see if it is being managed or has progressed to type 2 diabetes.


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