3. Fasting Insulin with Fasting Glucose: Catching Insulin Resistance Early
What it is: Fasting insulin and fasting glucose are two sides of the same coin. Fasting glucose tells you your baseline blood sugar when you haven't eaten. Fasting insulin tells you how hard your pancreas is working to keep that glucose in check.
When you measure both together, you can calculate HOMA-IR (Homeostatic Model Assessment for Insulin Resistance) which is a simple score that estimates how insulin resistant you actually are.
Why it matters: Insulin resistance is often the first domino to fall in metabolic disease. It shows up years before your A1c rises, before you're diabetic, before you gain weight. Catching it early means you can intervene with lifestyle changes — better sleep, strength training, refined carb reduction — before it cascades into prediabetes or type 2 diabetes. It's also linked to inflammation, PCOS, fatty liver disease, and accelerated aging.
4. HbA1c: Your 3-Month Blood Sugar Report Card
What it is: HbA1c measures the percentage of your red blood cells coated with glucose over the past 2–3 months. Unlike a single fasting glucose measurement (which is a snapshot), HbA1c is an average; it tells you how your blood sugar has been behaving over weeks, not just that morning.
Why it matters: HbA1c is the gold standard for diagnosing prediabetes and diabetes, but it's also useful for tracking how well your metabolic health is trending over time. The gap between your fasting insulin (early signal) and your HbA1c (later signal) tells you something important: if insulin is rising but A1c is still normal, you've caught insulin resistance in its early stages. Once A1c starts climbing, the metabolic damage is more advanced.
5. Cystatin C & eGFR: A Better Picture of Kidney Function
What it is: Most standard labs estimate kidney function using creatinine, a waste product from muscle metabolism. The problem: creatinine depends on how much muscle you have. So an older adult with less muscle, an endurance athlete, or someone who's lost weight might have "normal" creatinine but actually declining kidney function.
Cystatin C is a better marker. It's filtered by your kidneys but doesn't depend on muscle mass, so it catches kidney decline that creatinine-based estimates miss. When converted to eGFR (estimated glomerular filtration rate), it gives a cleaner picture of true kidney function.
Why it matters: Your kidneys filter waste, regulate blood pressure, and influence red blood cell production. Declining kidney function is often silent — you won't feel it until it's significant. By the time symptoms show up, damage is done. Measuring cystatin C-based eGFR gives you an early, accurate signal that kidney function is declining, letting you adjust medications, hydration, and other factors before it becomes a problem.
Final Thoughts: Making Data Work for You
Standard annual labs catch disease. These five biomarkers catch risk — the metabolic signals that precede disease by years or even decades. The goal isn't to become obsessed with numbers. It's to have clarity. To know your cardiovascular particle burden. To understand whether insulin resistance is creeping in. To catch kidney decline before it matters. These tests give you the information to make decisions now that protect your health later.
If longevity means anything, it means staying ahead of the curve by measuring what matters, understanding what it means, and acting before you have to. That's preventive medicine. That's taking control of your health story instead of waiting for someone else to write it for you.
Beyond foundational health markers, your biomarkers also play a critical role in how your body performs during exercise and recovers afterward. Learn how specific biomarkers impact your workout performance and recovery to optimize your fitness strategy alongside your longevity goals.
These five biomarkers are worth discussing with your doctor. For those focused on healthspan, Thrive’s baseline labs include all five—because better decisions start with better data.
This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.
