7 Numbers Your Doctor Checks That Predict How Long You'll Live
These biomarkers sit quietly in your lab results — and they're probably more revealing than your doctor lets on.
Your doctor orders blood work, glances at a few numbers, tells you everything looks “fine,” and sends you on your way. But buried in that printout — sometimes flagged, often not — are measurements that researchers now use to estimate biological age, future disease risk, and, yes, roughly how many years you have left if nothing changes. Some of these numbers you’ve probably heard of. Others your doctor may have never even mentioned by name. All of them are backed by serious population-scale research. This isn’t alternative medicine. This is what the science actually says.
Here’s the part worth sitting with before we get into the list: most of these markers respond to behavior. Diet, exercise, sleep, stress — they all show up here. Which means knowing your numbers isn’t just morbid curiosity. It’s an actual plan. Let’s go. 🔬
1. VO2 max: the single strongest predictor of how long you’ll live
If you could only pick one number to know — and I think you should know all seven — it’s probably VO2 max. This is the maximum amount of oxygen your body can use during intense exercise, measured in milliliters of oxygen per kilogram of body weight per minute. Your heart, lungs, blood vessels, and muscles all have to work together to push this number up. And the research on what it predicts is, frankly, alarming.
A landmark study of 122,007 adults published in JAMA Network Open found that the least-fit group had roughly five times the all-cause mortality of the elite-fit group. A 2024 overview of meta-analyses published in the British Journal of Sports Medicine, covering 199 unique cohort studies and more than 20.9 million observations, concluded that cardiorespiratory fitness is a strong and consistent predictor of morbidity and mortality among adults. That’s not one study with a quirky sample. That’s an umbrella review of 20 million people.
Research published in JAMA found that every 1-MET increase in VO2 max reduces mortality risk by 13 to 15 percent — and a MET is not a dramatic jump. It’s achievable with consistent training. VO2 max outperforms smoking, obesity, and hypertension as a predictor of survival in large-scale studies, and the association shows up with unnerving clarity.
What most people don’t realize is that VO2 max is trainable at any age. The most efficient approach isn’t grinding out marathon miles. It’s a combination of:
Zone 2 aerobic work (long, slow, conversational-pace cardio, 3–4 times per week)
High-intensity interval training — 4×4 Norwegian-style intervals work particularly well
Consistency over years, not weeks
Reduced sitting time, which independently suppresses cardiorespiratory fitness
Your doctor probably doesn’t measure VO2 max directly — it usually requires a treadmill or bike test with a metabolic analyzer. But most longevity-focused physicians and sports medicine clinics offer it, and it’s worth the trip. 💪 If you want to get a rough proxy at home, use the Cooper 12-minute run test or a tracked cycling effort. Not perfect, but directionally useful.
I think VO2 max deserves its own appointment. If your number is in the bottom quartile for your age and sex, that’s a five-alarm signal — not for anxiety, but for action.
2. Grip strength: your body’s brutal little truth-teller
This one surprises people, which is exactly why I love it. 💡 Grip strength — measured with a simple hand dynamometer — turns out to be one of the best single-point predictors of mortality your doctor can assess without drawing any blood.
A landmark Lancet study of nearly 140,000 people across 17 countries found that for every 5 kg decrease in grip strength, all-cause mortality risk rose 16 percent, cardiovascular death risk increased 17 percent, and stroke risk climbed 9 percent. Grip strength outperformed systolic blood pressure as a predictor of death from any cause.
A meta-analysis of 42 studies covering more than 3 million participants confirmed grip strength as an independent predictor of all-cause mortality, with each 5 kg decrease associated with a 16 percent rise in mortality risk. And more recently, research published in BMC Geriatrics in 2025 found that lower grip strength correlates with faster DNA methylation age acceleration — meaning your cells are literally aging faster at the epigenetic level.
Why does squeezing harder predict longer life? Because grip strength is a window into your overall neuromuscular reserve. It reflects muscle mass, neural efficiency, protein metabolism, and physical activity over years. It’s the readout, not the cause. A weak grip signals sarcopenia — the age-related muscle loss that accelerates frailty, falls, metabolic dysfunction, and cognitive decline. 🧬
You can test yourself right now. Healthy adults under 60 should generally be able to hold a dead-hang from a pull-up bar for at least 60 seconds — a rough proxy without a dynamometer. The LongevityHub guide to affordable longevity technologies mentions grip dynamometers as one of the most cost-effective ways to track this at home, and they’re correct — you can get a decent one for under $30.
The intervention is resistance training. Not cardio, not stretching — lifting things. Heavy compound movements like deadlifts, rows, and farmer’s carries build exactly the kind of whole-body strength that grip strength reflects. The good news: it works at any age. Studies show meaningful strength gains even in people in their 80s and 90s.
3. Fasting glucose and HbA1c: what sugar actually does to your clock ⏱️
Every cell in your body runs on glucose. But chronically elevated glucose — the kind that lingers slightly above normal for years — causes damage that accumulates quietly and shows up decades later as cardiovascular disease, kidney failure, cognitive decline, and cancer. This is why HbA1c (glycated hemoglobin, a three-month average of blood sugar control) and fasting glucose matter so much, even in people who have never been diagnosed with diabetes.
A 2025 study examining blood biomarkers among centenarians in Catalonia, Spain, found that glucose markers “play a critical role in survival to extreme old age,” with glycemic balance as measured by HbA1c and fasting glucose emerging as key factors in whether people made it to 100.
Studies of centenarians consistently show that blood glucose levels and the prevalence of diabetes are lower in those who reach 100 than in those who don’t. That pattern shows up in Italian centenarians, Chinese centenarian cohorts, and Polish centenarians independently. This isn’t one cultural fluke. It’s the same signal everywhere. 🌍
Research from the EPIC-Potsdam study, one of the largest nutrition-and-health cohorts in Europe, pointed specifically to markers linked to insulin sensitivity as predictors of healthy aging free from chronic disease — which is really what you’re optimizing for. Living to 95 while managing three chronic conditions is a very different proposition from living to 85 with full physical and cognitive function.
What are the target numbers?
Fasting glucose: ideally below 90 mg/dL (5.0 mmol/L). Standard labs often call anything under 100 “normal.” That’s a meaningful difference.
HbA1c: ideally below 5.4%. Pre-diabetes starts at 5.7%, but the risk gradient begins well before the diagnostic cutoff.
The routes to better glycemic control are well-established:
Reduce refined carbohydrates and ultra-processed food
Build lean muscle (muscle tissue is a major glucose sink)
Walk after meals — even 10 minutes blunts post-meal blood sugar spikes significantly
Prioritize sleep (sleep deprivation reliably worsens insulin sensitivity within days)
Consider continuous glucose monitoring if you want real data on your personal response
The LongevityHub piece on longevity supplements with actual evidence notes that omega-3 and vitamin D both show modest effects on metabolic markers — worth reading alongside the behavioral changes above.
4. High-sensitivity CRP: the inflammation signal your labs probably underreport 🔥
C-reactive protein, measured by the high-sensitivity assay (hs-CRP), is a protein your liver releases into the blood in response to inflammation. In acute illness, CRP spikes dramatically. But the longevity story isn’t about acute illness — it’s about chronic, low-grade, smoldering inflammation that persists for years and slowly damages nearly every organ system.
Researchers have given this phenomenon a name: inflammaging. Inflammaging — a description of low-grade, chronic, systemic inflammation in aging — is a highly significant risk factor for both morbidity and mortality in elderly people, as most age-related diseases share inflammatory pathogenesis. That includes atherosclerosis, type 2 diabetes, Alzheimer’s disease, and several cancers.
Elevated CRP levels above 3.0 mg/L are associated with an increased risk of cardiovascular events and mortality. Data from 1,447 elderly adults in the Chinese Longitudinal Healthy Longevity Survey demonstrated a graded association between higher hs-CRP levels and increased mortality. The gradient is real: more inflammation, earlier death, across multiple independent cohorts. 💊
The frustrating thing about hs-CRP in clinical practice is that it doesn’t come with a dramatic diagnosis. A reading of 2.8 mg/L won’t get a red flag on your standard lab printout. But it might represent years of systemic inflammation doing its quiet damage. Three risk categories matter:
Below 1.0 mg/L: low cardiovascular risk
1.0–3.0 mg/L: intermediate risk
Above 3.0 mg/L: high risk — and at this level, the research on all-cause mortality gets more urgent
The things that reliably reduce chronic inflammation are probably not surprising, but the magnitude of their effect might be:
Sleep (poor sleep acutely raises CRP within days)
Aerobic exercise, particularly Zone 2 cardio
An anti-inflammatory diet emphasizing omega-3s, polyphenols, and fiber
Gum health — periodontal disease generates systemic inflammation that shows up in CRP readings
Reducing visceral fat, which secretes pro-inflammatory cytokines continuously
If you’re a regular reader of this publication, you’ve probably seen how recovery and sleep show up in the LongevityHub deep dive on recovery as a longevity tool — the connection to inflammaging makes the sleep piece even more non-negotiable.
5. ApoB: the lipid number that actually tells you your cardiovascular risk 🫀
Here’s where I get genuinely frustrated with standard medical practice. Most lipid panels measure LDL cholesterol — the number most people recognize as “bad cholesterol.” The problem is that LDL-C measures the amount of cholesterol carried inside a type of particle, not the number of particles themselves. And it turns out the number of particles is what matters.
ApoB (apolipoprotein B) is the structural protein that sits on every single atherogenic lipoprotein particle. One ApoB = one particle. So ApoB is a direct particle count, and particle count is what predicts plaque buildup in arteries.
Evidence suggests that LDL-C and non-HDL-C may underestimate ApoB, potentially obscuring residual cardiovascular risk in many patients. A prospective case-control study published in late 2025 confirmed that ApoB is a reliable predictor of coronary artery disease, independent of LDL-C. It’s not that LDL-C is useless — it’s that ApoB is more precise, and in a sizable fraction of patients, the two diverge in clinically important ways.
Consider: you could have an LDL-C of 110 mg/dL (which looks acceptable) but a particle count that signals genuinely elevated risk. Or the reverse. Without ApoB, you don’t know which situation you’re in. 🧬
The National Lipid Association’s recent expert consensus proposed stratified ApoB targets:
Below 90 mg/dL for intermediate-risk individuals
Below 70 mg/dL for high-risk individuals
Below 60 mg/dL for very high-risk individuals
The interventions that lower ApoB are similar to those that lower LDL-C: reducing saturated fat, increasing soluble fiber, losing visceral fat, and in many cases, statins or newer lipid-lowering therapies like PCSK9 inhibitors. But you can’t optimize what you’re not measuring. Ask your doctor specifically for ApoB at your next lipid panel. It’s usually covered by insurance and most labs can run it from the same blood draw.
6. Blood pressure: even “normal” might be too high 💡
Systolic blood pressure — the top number — is probably the biomarker on this list your doctor watches most carefully. And for good reason. Hypertension is the world’s single largest modifiable risk factor for cardiovascular disease and stroke. But the interesting research isn’t about the known danger of high blood pressure. It’s about where the optimal target actually sits.
The traditional clinical threshold — 140/90 mmHg — is where treatment typically begins. But the question of what’s ideal for long-term survival has shifted considerably. A 2025 meta-analysis of five randomized controlled trials covering nearly 40,000 patients found that intensive systolic blood pressure control below 120 mmHg was associated with reduced all-cause mortality compared to standard control targeting below 140 mmHg.
The 2025 US hypertension guidelines reflected this evidence by revising targets downward, and the American Heart Association updated its Life’s Essential 8 framework to emphasize tighter blood pressure goals. For longevity purposes, a systolic reading consistently in the 110–120 range is where the data suggests the lowest risk sits, provided this is achieved without medication side effects or other complications. ⚡
What drives blood pressure down without medication?
Aerobic exercise: 30 minutes of moderate cardio most days can reduce systolic pressure by 5–8 mmHg
Dietary sodium reduction: meaningful for those who are salt-sensitive
Weight loss: particularly visceral fat reduction
Potassium and magnesium intake (most people are chronically low)
Sleep quality (elevated cortisol from poor sleep raises blood pressure)
Stress management and breathing techniques — there’s more evidence here than many doctors acknowledge
Track your blood pressure at home, not just at the clinic. White-coat hypertension is real, but masked hypertension — where readings look fine at the office but are elevated at home — is equally common and equally dangerous. A decent home cuff costs under $50 and is one of the most useful purchases in preventive medicine.
7. eGFR: your kidneys are keeping score, whether you check or not 🧪
Estimated glomerular filtration rate (eGFR) measures how well your kidneys are filtering waste from the blood. Your kidneys process roughly 200 liters of blood per day. When this filtration rate declines, the damage is cumulative, often symptom-free for years, and strongly predictive of cardiovascular events and mortality.
Studies have demonstrated that the risks of progressive chronic kidney disease, all-cause mortality, cardiovascular mortality, and all-cause hospitalization begin to increase at eGFR levels below 60 mL/min/1.73 m². The 2025 Catalonia centenarian study flagged creatinine and eGFR among the biomarkers that differentiated those who made it to 100 from those who didn’t — lower creatinine (indicating better kidney function) was associated with greater longevity.
This matters for several reasons. First, declining kidney function affects your ability to clear drugs, toxins, and metabolic waste — it accelerates the dysfunction of other systems. Second, eGFR decline is often reversible or at least stoppable if caught early. Third, most people with mildly reduced eGFR have no symptoms whatsoever. The only way to know is to test.
Healthy eGFR targets by age:
Under 60: above 90 mL/min/1.73 m² is ideal
Ages 60–70: above 75 is generally healthy; the natural decline with age is real but shouldn’t be rapid
The key isn’t just a single reading — it’s the trajectory. A slow decline matters less than a fast one.
The interventions that protect kidney function overlap considerably with everything else on this list: blood pressure control (hypertension is the second leading cause of kidney failure after diabetes), blood sugar management, avoiding nephrotoxic drugs where possible, staying hydrated, and maintaining a healthy body weight. Limiting excessive protein intake may also matter for those already showing eGFR decline — worth discussing with a physician rather than guessing.
What to do with all of this
Here’s the practical question: how many of these seven numbers do you actually know? Most people can name their LDL cholesterol. Fewer know their HbA1c. Almost nobody outside a sports medicine clinic has heard their VO2 max. And yet the research above — from multiple independent teams, across dozens of countries, covering millions of people — suggests these numbers collectively paint a far more accurate picture of where you’re headed than any individual metric.
This isn’t an argument to become obsessed with your biomarkers or to panic over a slightly elevated CRP. It’s an argument to take a more active role in understanding your own data. Ask your doctor specifically for:
VO2 max (or a fitness test referral)
ApoB in addition to LDL-C on your next lipid panel
- Hs-CRP
Grip strength (some primary care offices measure it, some don’t — a dynamometer at home works fine)
HbA1c if it’s not already in your routine labs
eGFR trajectory over time, not just a single reading
The LongevityHub self-assessment guide offers a useful framework for pulling these threads together if you want a starting point. And the mTOR explainer is worth reading if you want to understand the cellular mechanisms that connect most of these markers to aging itself.
One last thought: these numbers don’t exist in isolation. A body with excellent VO2 max, low inflammation, stable blood sugar, and strong kidneys is a body that tends to have good grip strength, healthy blood pressure, and clean lipid particles. The biomarkers reinforce each other because they reflect the same underlying system — a body being used well or not. The goal isn’t a perfect lab report. It’s a life where these numbers stay healthy because the life that’s generating them is healthy.
So here’s the question worth sitting with this week: which of these seven numbers have you never actually checked — and why not?