What is glucose?
Glucose is the sugar that circulates in your blood and the main source of energy for your cells. It comes mostly from the carbohydrates you eat. Insulin, a hormone made by the pancreas, helps glucose enter your cells so it can be used for energy.
When this system works well, glucose rises after eating and returns to its range within a few hours. When it stays high often, it can be a sign that the body has trouble processing carbohydrates.
How it's measured
The two most common tests are fasting glucose, which shows the value at a given moment, and glycated hemoglobin (A1c), which reflects the approximate average over the last three months.
| Reference | Fasting glucose | A1c |
|---|---|---|
| Usual range | Below 100 mg/dL | Below 5.7 % |
| Prediabetes | 100 – 125 mg/dL | 5.7 – 6.4 % |
| Diabetes | 126 mg/dL or higher | 6.5 % or higher |
Source: American Diabetes Association (ADA), diagnostic criteria. A diagnosis requires medical confirmation.
Why it matters
Persistently high glucose is associated with a higher risk of type 2 diabetes and cardiovascular problems. Many people have no symptoms at first, so measuring it is the most reliable way to know where you stand.
- Family history of diabetes
- Large waist circumference or excess weight
- Low physical activity or high blood pressure
What else to measure
Hemoglobin A1c
Complements fasting glucose with an average over several months.
Waist circumference
Abdominal fat is closely linked to insulin sensitivity.
Blood pressure and lipids
Complete the picture of your metabolic and cardiovascular health.
