Why it matters
Diabetes is common in South Africa. The 2016 South African Demographic and Health Survey found that about 13% of women and 8% of men aged 15 and older had diabetes. Many more people have raised blood sugar that hasn't reached that level yet. Finding it early gives you time to act.
The main blood sugar tests
HbA1c
HbA1c reflects your average blood sugar over roughly the past two to three months. You don't need to fast for it.
Fasting plasma glucose
This measures your blood sugar after at least eight hours without food.
Oral glucose tolerance test (OGTT)
You drink a measured sugar drink after fasting, and your blood sugar is checked two hours later. It is more involved, and is used in specific situations, including pregnancy.
What do the numbers mean?
| Test | Normal | Prediabetes | Diabetes |
|---|---|---|---|
| HbA1c | below 5.7% | 5.7% to 6.4% | 6.5% or higher |
| Fasting glucose | below 5.6 mmol/L* | 5.6 to 6.9 mmol/L* | 7.0 mmol/L or higher |
| 2-hour OGTT | below 7.8 mmol/L | 7.8 to 11.0 mmol/L | 11.1 mmol/L or higher |
*Guidelines differ slightly on the lower fasting cut-off. The American Diabetes Association uses 5.6 mmol/L. The World Health Organization criteria, also used in South African laboratory guidance, define impaired fasting glucose as 6.1 to 6.9 mmol/L. Your doctor will interpret your results in context.
Important: a diagnosis of diabetes is usually confirmed with a repeat test, unless there are clear symptoms. One result on its own is not the full picture, and some conditions (such as anaemia or certain haemoglobin variants) can affect HbA1c.
Who should be tested?
South African laboratory guidance, based on international recommendations, suggests testing:
- adults who are overweight (BMI above 25, or above 23 for people of Asian Indian descent) and have at least one other risk factor;
- everyone from age 45, even without risk factors.
Risk factors include physical inactivity, high blood pressure, a parent or sibling with diabetes, abnormal cholesterol, PMOS (polyendocrine metabolic ovarian syndrome, previously called PCOS), diabetes in a previous pregnancy or having had a large baby, heart disease, and previous borderline results.
Is prediabetes reversible?
For many people, yes, or at least its progression can be slowed significantly.
In the landmark Diabetes Prevention Program, adults with raised blood sugar who aimed for about 7% weight loss and at least 150 minutes of physical activity a week reduced their risk of developing type 2 diabetes by 58% over about three years. A medicine (metformin) reduced risk by about 31%.
Helpful steps include:
- regular activity, including strength training;
- fewer sugary drinks and refined carbohydrates;
- more fibre, vegetables, legumes and protein;
- seven or more hours of sleep a night;
- stopping smoking;
- gradual weight loss if you carry excess weight.
When to see a doctor
See your doctor if you:
- have any of the risk factors above and haven't been tested;
- are 45 or older and haven't been tested recently;
- have a result in the prediabetes range;
- have symptoms such as unusual thirst, passing more urine, unexplained weight loss, blurred vision or frequent infections. Don't wait for a routine check in this case.
Frequently asked questions
What is a normal HbA1c?
Below 5.7% is generally considered normal. Your doctor may set different targets if you already have diabetes.
Can I feel prediabetes?
Usually not. That's why testing matters.
How often should I be retested?
Commonly cited intervals range from every few months for higher-risk people to every three years for lower-risk people. Your doctor will advise you.
Does eating sugar cause diabetes?
Type 2 diabetes develops from a mix of genetics, body weight, activity, diet and other factors. Sugary drinks in particular are linked to higher risk, so cutting them is a sensible first step.
References
- National Department of Health, Stats SA, SAMRC and ICF. South Africa Demographic and Health Survey 2016: Key Findings. https://www.dhsprogram.com/pubs/pdf/DM142/DM142.pdf
- Du Plessis M. Screening and diagnosis of diabetes mellitus using glucose testing. Ampath PathChat. 2018. https://www2.ampath.co.za/resources/screening-and-diagnosis-of-diabetes-mellitus-using-glucose-testing
- NIDDK. Insulin resistance and prediabetes. https://www.niddk.nih.gov/health-information/diabetes/overview/what-is-diabetes/prediabetes-insulin-resistance
- American Diabetes Association. Standards of Care in Diabetes: Diagnosis and Classification.
- Diabetes Prevention Program Research Group. New England Journal of Medicine. 2002.
This article is for general educational purposes only, like a health newsletter. It is not medical advice, diagnosis or treatment, and reading it does not create a doctor and patient relationship. Please speak to your own doctor about your situation. In an emergency, call 10177 or 112, or go to your nearest emergency unit.