How to Read Your Blood Test Results

Why most people ignore the most powerful health data they have

Every year, millions of people get blood tests and glance at the results just long enough to see "within normal range" before filing them away. But those numbers — glucose, cholesterol, thyroid hormones, liver enzymes — are the closest thing we have to a real-time dashboard of what is happening inside your body.

The problem is not the data. It is that nobody teaches you how to read it.

The difference between "normal" and "optimal"

Standard lab reference ranges are built from population averages. If 95% of people who walk into a lab have a fasting glucose between 3.9 and 5.6 mmol/L, that becomes the reference range. But population average is not the same as optimal for longevity.

Longevity medicine uses tighter, evidence-based ranges. For example:

• Fasting glucose: Lab normal is up to 5.6 mmol/L. Optimal for longevity is under 4.8 mmol/L.
• HbA1c: Lab normal is under 5.7%. Longevity optimal is under 5.2%.
• LDL cholesterol: Lab normal can be up to 3.4 mmol/L. Optimal is under 2.6 mmol/L — and for people with risk factors, under 1.8 mmol/L.
• HDL cholesterol: Lab normal starts at 1.0 mmol/L for men. Optimal is above 1.5 mmol/L.

This gap between "normal" and "optimal" is where chronic disease quietly develops over decades.

Key markers and what they mean

Metabolic panel

Fasting glucose measures how much sugar is in your blood after an overnight fast. Consistently elevated glucose — even within the normal range — is an early warning sign of insulin resistance, the root cause of type 2 diabetes and a driver of cardiovascular disease.

HbA1c (glycated haemoglobin) reflects your average blood sugar over the past 2-3 months. It is more reliable than a single glucose reading because it captures the trend, not just a snapshot.

HOMA-IR is calculated from fasting glucose and fasting insulin. It is the gold standard for measuring insulin resistance. A HOMA-IR above 1.5 suggests early metabolic dysfunction, even if glucose and HbA1c look normal.

Lipid panel

Total cholesterol is less useful than its components. What matters is the ratio and particle composition.

LDL (low-density lipoprotein) carries cholesterol to your arteries. Elevated LDL is causal in atherosclerosis — this is one of the most well-established findings in medicine.

HDL (high-density lipoprotein) carries cholesterol away from your arteries. Higher is generally better. Low HDL combined with high triglycerides is a metabolic red flag.

Triglycerides are a type of fat in your blood. Elevated triglycerides, especially fasting, signal insulin resistance and increased cardiovascular risk. The triglyceride-to-HDL ratio is a powerful metabolic health indicator.

Thyroid function

TSH (thyroid-stimulating hormone) is the standard screening test. But TSH alone misses subclinical thyroid dysfunction. A TSH of 3.5 mIU/L is technically normal, but many functional medicine practitioners consider optimal to be between 0.5 and 2.0 mIU/L.

Free T3 and Free T4 are the active thyroid hormones. If your TSH is normal but you still feel fatigued, cold, or unable to lose weight, checking Free T3 can reveal conversion issues that TSH alone will miss.

Iron and nutrients

Ferritin is your iron storage marker. Low ferritin is the most common nutritional deficiency in the world and causes fatigue, brain fog, and impaired exercise performance long before anaemia develops. Optimal ferritin is between 40 and 100 ng/mL.

Vitamin D is technically a hormone, not a vitamin. Deficiency is linked to immune dysfunction, depression, osteoporosis, and increased cancer risk. The lab normal range starts at 30 ng/mL, but longevity research suggests 50-70 ng/mL is optimal.

How Gemut Health helps

Gemut Health automatically parses your blood test PDF, extracts every marker, and compares each one against both standard and longevity-optimised reference ranges. You see instantly which markers are optimal, borderline, or elevated — and what to do about them.

Instead of a wall of numbers, you get a clear health score, trend tracking across multiple panels, and an AI-generated action plan tailored to your specific results.

The first step is knowing your numbers. The second step is understanding what they mean. Gemut Health handles both.