Warm scene with a traffic-light metaphor: green, yellow, red. Prediabetes is the yellow zone between healthy and diabetes, a warning sign that can be influenced favourably.
The yellow zone
Prediabetes lies between
healthy and diabetes –
and can be influenced well.
A warning sign, not a verdict – you can often steer back.
The term prediabetes describes a state in which blood sugar is above the normal range but hasn’t yet reached the diabetes threshold.1 Important: prediabetes isn’t a disease in its own right but a risk state – and a good moment to steer back.
The three routes to classification
There are three recognised measurements. Under the criteria of the American Diabetes Association (ADA), just one of them in the relevant range is enough:12
Table of the three measurements per the ADA: fasting glucose normal below 100, prediabetes 100 to 125, diabetes 126+ mg per decilitre. Two-hour value in the glucose tolerance test normal below 140, prediabetes 140 to 199, diabetes 200+. HbA1c normal below 5.7 percent, prediabetes 5.7 to 6.4 percent, diabetes from 6.5 percent.
The three routes to diagnosis
Thresholds per ADA – one of them is enough to classify
Measurement
normal
Prediabetes
Diabetes
Fastingglucose
below 100
100–125
126+
2-hour value(glucose test)
below 140
140–199
200+
HbA1c
below 5.7%
5.7–6.4%
6.5%+
mg/dl
mg/dl
Note: the WHO sometimes sets the lower fasting limit at 110 mg/dl. OGTT and HbA1c often don’t capture the same people.
A single threshold isn’t a diagnosis – the medical assessment counts.
Why steering back pays off
Evidence level: established
Risk rises continuously with the value – and prediabetes isn’t a one-way street. Large prevention studies show that lifestyle measures can markedly delay or prevent progression to type 2 diabetes.1 The most effective levers are more movement, reducing belly fat and a fibre-rich diet.
What prediabetes actually is
Prediabetes isn’t a disease of its own but a precursor: blood sugar is already elevated but not yet in the diabetic range. Behind it is usually growing insulin resistance – cells respond less well to insulin, and the pancreas has to make more of it. The tricky part: prediabetes doesn’t hurt and usually causes no symptoms. It’s almost always found by chance in a blood test.
Who is particularly at risk
Risk rises above all with these factors:
- Abdominal overweight – fat in the belly especially drives insulin resistance.
- Family history – type 2 diabetes in parents or siblings.
- Lack of movement and a mostly sedentary day.
- Older age and a previous gestational diabetes.
Important: prediabetes is a warning sign, not a one-way street. In many people, blood sugar can be normalised again in this phase.
How to steer back, concretely
The most effective levers are well documented and practical:
- Movement: around 150 minutes per week of moderate activity – brisk walks count too.4
- Weight: even 5–7% less body weight markedly lowers risk.4
- Plate: more fibre and fewer fast carbs flatten the spikes.
- Walk after eating: 10–15 minutes noticeably dampen the rise.
Key takeaways
- Prediabetes = grey zone between normal and diabetes, a warning sign.
- Fasting glucose 100–125 mg/dl, OGTT-2h 140–199 mg/dl, HbA1c 5.7–6.4%.
- One value in the borderline range is enough to classify – but the tests don’t capture the same people.
- Lifestyle can markedly delay or prevent progression.
- Most effective levers: movement, less belly fat, fibre, post-meal walks.
Sources
Sources as of: 21 Jul 2026.
- Diagnostic criteria for prediabetes/diabetes (fasting, HbA1c, OGTT). American Diabetes Association. diabetes.org
- Prediabetes categories and overlap between tests (fasting, OGTT, HbA1c). Reference/guideline. ncbi.nlm.nih.gov
- WHO: intermediate hyperglycaemia / impaired fasting glucose thresholds. who.int
- ~150 min/week activity plus 5–7% weight loss delay/prevent type 2 diabetes (Diabetes Prevention Program). canr.msu.edu