Conditions
Prediabetes and type 2 diabetes: what to know
How prediabetes and type 2 diabetes are diagnosed, early symptoms, who should be tested, and the lifestyle changes proven to prevent or delay diabetes.
Key takeaways
- More than 1 in 3 US adults has prediabetes, and most do not know it.
- A simple blood test — A1C or fasting glucose — can diagnose prediabetes and diabetes.
- Losing 5–7% of body weight and being active can greatly reduce the risk of developing diabetes.
Type 2 diabetes develops when the body does not respond well to insulin and cannot keep blood sugar in a healthy range. It usually develops slowly, often over years, through a stage called prediabetes — blood sugar that is higher than normal but not yet in the diabetes range.
Diagnosis
| Test | Normal | Prediabetes | Diabetes |
|---|---|---|---|
| A1C | below 5.7% | 5.7–6.4% | 6.5% or higher |
| Fasting glucose | below 100 mg/dL (5.6 mmol/L) | 100–125 mg/dL | 126 mg/dL (7.0 mmol/L) or higher |
A diagnosis of diabetes is usually confirmed with a repeat test unless symptoms are obvious.
Symptoms
Prediabetes usually has none. Type 2 diabetes may cause increased thirst, passing urine often, tiredness, blurred vision, slow-healing cuts, frequent infections, and tingling in the hands or feet. Many people have no symptoms at diagnosis.
Who should be tested
In the US, testing is recommended for adults aged 35 to 70 who have overweight or obesity, and earlier for people with risk factors such as a family history of diabetes, a history of gestational diabetes, polycystic ovary syndrome, high blood pressure or abnormal cholesterol. People of South Asian, Black, Hispanic, Indigenous and Pacific Islander backgrounds have a higher risk and may benefit from earlier testing.
Preventing or delaying diabetes
Large studies show that structured lifestyle programs can cut the risk of progressing from prediabetes to type 2 diabetes by more than half:
- Lose 5–7% of body weight if you have overweight — about 5 kg (11 lb) for a person weighing 90 kg.
- Be active for at least 150 minutes a week, such as brisk walking.
- Eat more fibre from vegetables, beans, whole grains and fruit, and fewer sugary drinks and refined carbohydrates.
- Sleep 7 or more hours and stop smoking.
Ask your clinician about recognised diabetes prevention programs in your area.
Living with type 2 diabetes
Treatment combines lifestyle changes with medicines when needed — commonly metformin first, and newer medicines that also protect the heart and kidneys for some people. Regular checks include A1C, blood pressure, cholesterol, kidney tests, eye exams and foot checks. Some people, especially soon after diagnosis, reach remission with significant weight loss.
Seek urgent care for very high blood sugar with vomiting, confusion, deep or fast breathing, or extreme drowsiness, and for low blood sugar that does not improve with fast-acting sugar.
Use our healthy weight and waist-to-height tools, watch Cleveland Clinic’s explainer in our video library, or get matched with a primary care clinic.
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