Fasting Glucose
Blood sugar level measured after an overnight fast — a basic but important metabolic marker.
Optimal Range
72-85 mg/dL (optimal) · < 100 mg/dL (normal)
Risk-Stratified Targets
| Population / Context | Target |
|---|---|
| Optimal (longevity) | 72–85 mg/dL |
| Normal | < 100 mg/dL |
| Prediabetic (impaired fasting glucose) | 100–125 mg/dL |
| Diabetic | ≥ 126 mg/dL |
Why It Matters
Fasting glucose reveals baseline blood sugar regulation. Levels above 85 mg/dL, while clinically 'normal,' are associated with increased long-term metabolic and cardiovascular risk.
Understanding Fasting Glucose
Fasting glucose is one of the most fundamental metabolic biomarkers — a measurement of blood sugar concentration after an overnight fast of at least 8 hours. It reflects your body's ability to regulate glucose through insulin secretion and tissue sensitivity, providing a baseline snapshot of metabolic health.
Conventional medicine defines normal fasting glucose as below 100 mg/dL, with 100–125 mg/dL classified as prediabetic and 126 mg/dL or above as diabetic. However, longitudinal research suggests that cardiovascular and metabolic risk begins to increase at levels well below these thresholds. Studies have shown that fasting glucose levels above 85 mg/dL are associated with significantly higher rates of diabetes development and cardiovascular events compared to levels in the 70s.
Fasting glucose has an important limitation: it is one of the last metabolic markers to become abnormal in the progression toward type 2 diabetes. Insulin resistance typically develops years before fasting glucose rises, as the pancreas compensates by producing more insulin to maintain normal glucose levels. A fasting glucose of 90 mg/dL with a fasting insulin of 15 μIU/mL tells a very different story than a glucose of 90 with an insulin of 4 — the first suggests hidden insulin resistance, while the second suggests excellent metabolic health.
Key Research
Normal Fasting Plasma Glucose and Risk of Type 2 Diabetes Diagnosis
Nichols GA et al. · Am J Med (2008)
Key finding: Individuals with fasting glucose of 95–99 mg/dL had significantly higher risk of developing diabetes compared to those with glucose below 85 mg/dL, even though both groups are 'normal' by conventional standards.