What is diabetes?
Diabetes means blood sugar stays high because the body either can't make enough insulin (type 1) or doesn't respond to it properly—insulin resistance (type 2). Most adult diabetes is type 2, which is closely tied to excess weight, inactivity and family history.
This article is general health information and is not a substitute for diagnosis or treatment. If symptoms persist, see a doctor.
How is diabetes diagnosed?
| Test | Normal | Prediabetes | Diabetes |
|---|---|---|---|
| Fasting glucose (mg/dL) | Under 100 | 100–125 | 126 or higher |
| A1C | Under 5.7% | 5.7–6.4% | 6.5% or higher |
| 2-hour glucose (75 g OGTT) | Under 140 | 140–199 | 200 or higher |
These are the American Diabetes Association cutoffs (ADA, 2024); without symptoms, results are usually confirmed with a repeat test. Classic symptoms are extreme thirst, frequent urination and weight loss despite eating a lot, but early diabetes is usually silent.
Complications and prevention
Years of high blood sugar raise the risk of eye disease (retinopathy), kidney disease, nerve damage, heart attack and stroke. In the Diabetes Prevention Program, people with prediabetes who aimed for 7% weight loss and 150 minutes of exercise a week cut their risk of developing diabetes by 58%, versus 31% with metformin (Knowler et al., 2002). See also metabolic syndrome and fatty liver disease.
FAQ
- Is a fasting blood sugar of 110 diabetes?
- No. 100–125 mg/dL is prediabetes (impaired fasting glucose). Lifestyle changes can slow or stop progression.
- Does eating sugar cause diabetes?
- Not directly by itself; excess calories, weight, inactivity and genes all play a role, though sugary drinks are linked to higher risk.
Sources reviewed: 2026-10-25
References
- American Diabetes Association Professional Practice Committee. (2024). Standards of care in diabetes—2024. Diabetes Care, 47(Suppl. 1).
- Knowler, W. C., Barrett-Connor, E., Fowler, S. E., et al. (2002). Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. New England Journal of Medicine, 346(6), 393–403.