Fasting blood sugar measures glucose in your blood after at least 8 hours without eating. It's used to screen for prediabetes and diabetes. But like HbA1c, normal fasting glucose doesn't rule out insulin resistance.
What the numbers mean
| Fasting glucose | What it means |
|---|---|
| < 100 mg/dL | Normal |
| 100–125 mg/dL | Prediabetes |
| 126+ mg/dL | Diabetes (requires confirmation) |
A single high reading doesn't diagnose diabetes. The test is usually repeated or confirmed with HbA1c.
Why normal fasting glucose can be misleading
Insulin resistance can be present for years before fasting glucose rises. Your pancreas produces extra insulin to keep glucose normal, masking the underlying problem.
Meanwhile, insulin resistance is already driving the pattern that damages arteries: higher triglycerides, lower HDL, smaller denser LDL, higher blood pressure. More on this in our HbA1c guide.
Better ways to catch insulin resistance early
- Fasting insulin level: elevated (>10 µIU/mL) before glucose rises.
- Triglyceride-to-HDL ratio: above 2 suggests insulin resistance.
- HOMA-IR: calculated from fasting glucose and insulin together.
- Waist-to-height ratio: above 0.5 correlates with visceral fat and insulin resistance.
How to improve
The same strategies that improve HbA1c and insulin sensitivity:
- Cut refined carbs and added sugars.
- Exercise regularly (both cardio and resistance).
- Lose visceral fat.
- Sleep 7–8 hours.
- Manage stress.
The bottom line
Fasting glucose is one snapshot. Don't rely on it alone. Look at the full metabolic picture: triglycerides, HDL, waist size, fasting insulin if available. If those are off, act now.
Confidence in your heart health
A CT angiogram heart scan that gives you the full picture of your arteries, giving you clarity and the power to act early. Reserve your spot today.