October 02, 2026

Life by the Numbers - September 2026

The markers I monitor and why they matter for your long-term health

Every month I try to show you the why underneath a symptom or a diagnosis. Disease doesn’t start when a lab value turns abnormal. It starts years earlier.

This issue is about the earlier signals.

Insulin resistance can build for more than a decade before AIC moves. A woman can carry real metabolic risk at her waist with a completely normal BMI.

That’s why this issue uses thresholds and risk staircases instead of single cutoffs. The goal is to show you where the curve actually starts to bend, not just where the lab flags it. Body fat %, visceral fat, and central obesity all behave differently by sex, and treating one threshold as universal shortchanges half of you.

Some of these numbers you can move this week. A few you cannot move at all, and simply need to know. I’ve organized both kinds below, on purpose, so you can tell the difference.

Metabolic Markers

A1C & Glucose

A1C gives us an average. That is useful, but it does not show everything happening between meals or tell us when insulin sensitivity began to change. Here is why I look beyond one A1C result.

140 mg/dL = 2x

A single post-meal glucose spike above 140 mg/dL — even with a normal fasting glucose and A1C — is linked to double the risk of dying from cardiovascular disease.

A1C Risk Staircase

Caveat worth knowing: this is a U-shaped curve, not a straight line - both too-low and too-high A1C carry excess mortality risk. The clearest, most reproducible risk increase begins at the diabetes threshold (≥6.5%), not in the “normal” 5.5–6.4% range.

Glucose Variability & Spikes

Each 1 mmol/L rise in 2-hour postprandial glucose raises cardiovascular death risk 26% and all-cause death risk 10%, independent of metabolic syndrome status.⁵
In a study of adults with type 2 diabetes, spending 10 percentage points less time in the target glucose range - for example, 80% of the day instead of 90% - was linked with 8% higher risk of death from any cause and 5% higher risk of cardiovascular death. The study used a range of 70–180 mg/dL

Insulin: The Early Warning Sign

The Whitehall II study (6,538 people tracked prospectively) found that insulin sensitivity begins declining up to 13 years before a type 2 diabetes diagnosis.⁷
In the same data, fasting glucose stays essentially normal until just 3 years before diagnosis, then rises steeply — meaning insulin resistance can be active for a decade or more while your labs still read normal.⁷

The Takeaway

A1C alone can hide the problem — it's an average, and averages smooth over spikes. Eating protein and fiber before carbohydrates, and walking for 10 minutes after a meal, blunt the spike directly.

Cardiovascular Markers

Blood Pressure, Lp(a) & HRV These three measures belong in a conversation about heart health, but they tell us very different things. Blood pressure can change. Lp(a) is largely inherited. HRV can help you notice how you are recovering.

Every 20/10 mmHg increase in blood pressure → about 2× the risk

Across observational studies involving more than 1 million people, each 20-point increase in systolic blood pressure or 10-point increase in diastolic blood pressure was associated with roughly double the risk of death from heart disease or stroke. The relationship was seen from levels as low as 115/75.⁸

Blood Pressure Risk Staircase

In a separate analysis, every 10 mmHg reduction in systolic blood pressure with treatment was associated with about 20% fewer major cardiovascular events, 27% fewer strokes, and 28% fewer heart-failure events.¹⁰ Sustained hypertension has been linked to about 7.8 fewer years of life expectancy.¹¹

Lp(a): The Number You’re Born With

No universal safe cutoff but risk starts climbing above 30 mg/dL; clinical action threshold is ≥50 mg/dL (≥125 nmol/L).¹²
Each 1-SD increase in Lp(a) raises fatal/non-fatal CVD risk 12%, independent of cholesterol and other classic risk factors.¹³
Above 120 mg/dL (95th percentile): heart attack risk roughly triples.¹⁴
~80–90% genetically determined - diet and exercise barely move it. Know your number once; you can’t out train it.

HRV: Your Autonomic Early-Warning System

Low HRV is linked to a 32–45% higher risk of a first cardiovascular event in people with no prior heart disease.¹^,⁵
In people with existing cardiovascular disease, low HRV more than doubles all-cause mortality risk.¹^,⁶

The Takeaway

Blood pressure and Lp(a) are two different stories - one you can move with lifestyle and treatment, one you’re born with and simply need to know. HRV is your daily readout of how well your nervous system is tolerating the load. Track all three; address them differently.

Body Composition Markers

Body Fat % & Visceral Fat

A normal BMI can still miss what is happening around the waist. That is why I want to look at body fat and visceral fat, not just the number on the scale.

27%+ body fat in men and 44%+ body fat in women = 1.78x risk of death

Adults with a high body-fat percentage, 27% or more in men, 44% or more in women, had 78% higher risk of death from any cause over 15 years than those in the healthy range for their sex.²⁰

Body Fat % and Mortality Risk

Visceral Fat: Location Matters More Than Amount

Each 1-SD increase in visceral fat raises all-cause mortality risk 17% — while the same increase in subcutaneous fat is linked to a 19% lower risk. Same tissue type, opposite direction, depending on where it sits.¹⁸
People with the most visceral fat had a higher risk of death than those in the middle range: 24% higher in men and 11% higher in women.¹⁹
In women specifically, each 1-SD increase in visceral fat raises all-cause mortality risk 13–16%, while the same increase in subcutaneous fat is protective — and the visceral fat risk was concentrated in women who were already obese.²²
Normal BMI does not mean risk-free: postmenopausal women with a normal BMI but an elevated waist (“normal-weight central obesity”) had 31% higher all-cause mortality, 20% higher cancer mortality, and 25% higher cardiovascular mortality than normal-weight women without central obesity — a risk comparable to BMI-defined obesity itself.²³

The Takeaway

The scale number matters less than where the fat sits — and this is especially true for women, where a normal BMI can still hide real metabolic risk carried at the waist. Visceral fat responds well to zone 2 cardio, resistance training, and reducing added sugar/alcohol — a waist-to-height ratio under 0.5 is a simple at-home proxy worth tracking alongside body fat %, regardless of what the scale says.

Fitness & Strength Markers

VO₂ Max & Grip Strength

VO₂ max and grip strength are two markers I pay close attention to when we talk about longevity. They tell me about your fitness and strength now, and whether you are gaining or losing capacity over time.

Unfit > Smoking

Low cardiorespiratory fitness carried a HIGHER mortality risk (5.04x) than smoking (1.41x) in a 122,007-person Cleveland Clinic cohort — with no ceiling on the benefit of more fitness.²⁴

Fitness and Mortality Risk

In this treadmill study, people were compared with others of the same age and sex. “Low” means the bottom quarter of that group; “elite” means roughly the top 2%.²⁴

VO₂ Max: Tracking Aerobic Fitness Over Time

VO₂ max measures how much oxygen your body can use during hard exercise.
Across other studies, an increase of about 3.5 mL/kg/min in VO₂ max was linked with 11–17% lower all-cause mortality.²⁵
A decline of 1 mL/kg/min over 11 years was linked with 9% higher risk.²⁵,²⁶

Grip Strength: A Faster Signal Than It Sounds

Each 5 kg (about 11 pounds) decrease in grip strength is linked to a 16% higher all-cause mortality risk and a 21% higher cardiovascular mortality risk.²⁷
Grip strength was a stronger predictor of all-cause mortality than systolic blood pressure in a 140,000-person, 17-country study.²⁸
Lowest vs. highest grip strength category: 41% higher all-cause mortality risk, 63% higher cardiovascular mortality risk.²⁷

The Takeaway

VO2 max and grip strength are two of the most trainable numbers in this entire issue — unlike Lp(a), both respond directly to what you do this month. Zone 2 cardio builds the engine; loaded carries and grip work build the signal. Neither requires elite performance, just consistent direction.

Sleep Metrics

Duration, Insulin Resistance & Longevity

Before I start troubleshooting glucose or cravings, I want to know how you have been sleeping. Even short periods of restricted sleep can affect insulin sensitivity.

5 nights at 4 hours of sleep = -24% in insulin sensitivity

AJust 5 nights at 4 hours of sleep cut insulin sensitivity by 24% and blunted the acute insulin response by 30% - a preview of pre-diabetes, built in less than a week.³¹

Sleep Restriction & Insulin Sensitivity

Methods vary across these studies (oral glucose tolerance tests, insulin clamps) — but the direction is consistent: less sleep, less insulin sensitivity, within days.

Sleep Duration & Longevity

5 hours/night vs. 7 hours/night: 29% higher all-cause mortality risk.³²
In one large study, people who reported all five healthy sleep habits had a longer estimated life expectancy than those who reported only one or none: 4.7 years longer for men and 2.4 years longer for women, calculated from age 30.³³
- The five habits were sleeping 7–8 hours, having trouble falling asleep no more than twice a week, having trouble staying asleep no more than twice a week, waking up rested at least five days a week, and not using sleep medication.

The 7:1 Rule

7 hours of sleep, consistent night to night within a 1-hour window, is linked to up to +4 years of life expectancy — consistency matters as much as total hours.³⁴

The Takeaway

Sleep is a metabolic intervention, not just rest. Three bad nights measurably shifts insulin sensitivity in the wrong direction — the same direction as a poor diet. Before you troubleshoot glucose or cravings, ask about the last week of sleep. Consistency (the 7:1 rule) matters as much as total hours.

Dietary Quality

Fiber, Legumes, Fermented Foods & More

Diet is central to so many of the markers we’ve covered. What you eat can affect your blood sugar, body composition, and cardiovascular health over time, but different foods play different roles. The studies below look at what we know about fiber and legumes, protein, fermented foods, and ultra-processed foods.

10 Weeks of Fermented Food

In a randomized trial, adding fermented foods, not fiber, was what increased gut microbial diversity and lowered inflammatory markers over 10 weeks⁴⁰.

Caveat: a larger follow-up trial found fiber and fermented foods have distinct, not identical, effects on gut microbiota and immune markers - they aren’t interchangeable, each does something different.⁴²

Diet Changes & All-Cause Mortality

Fermented Foods: What the Trial Found

In a 10-week trial of 36 healthy adults, one group gradually increased fermented foods, such as yogurt, kefir, and kimchi, to about six servings a day. Their gut microbial diversity increased, and 19 of the 93 inflammatory blood proteins measured went down, including IL-6. The reductions were greater among those who ate more fermented foods. A second group increased fiber to 45 grams a day, but their microbial diversity did not change over the same period.⁴⁰,⁴¹

The Takeaway

If you can only make one change to your diet this month, add fermented food daily — a serving of yogurt, kefir, kimchi, sauerkraut, or kombucha. The randomized-trial evidence for this single swap is stronger than for fiber alone. Then build legumes and total fiber in behind it — they work on different levers, and the combination is the actual long-term goal.

A Closing Thought

None of these numbers are meant to be memorized in isolation — they are meant to give you a vocabulary for your own body. A blood pressure cuff, a CGM, a grip dynamometer, a sleep tracker: these are not gadgets, they are translators. They take what your cells have been experiencing quietly for years and turn it into a number you can actually act on.

If any of these numbers resonate, or worry you, schedule a check-in so we can apply them to your specific case, your specific labs, and your specific pathway.

Dr. Lechner

Resources

U-shaped A1C mortality curve — pmc.ncbi.nlm.nih.gov/articles/PMC10095266
A1C, CVD risk and spline analysis — pmc.ncbi.nlm.nih.gov/articles/PMC4603057
A1C threshold, Strong Heart Study — pmc.ncbi.nlm.nih.gov/articles/PMC3161283
A1C and heart failure, ARIC — pmc.ncbi.nlm.nih.gov/articles/PMC2911067
Postprandial glucose and CV death — diabetesjournals.org/care
Time-in-range and mortality — chcs.org
Whitehall II insulin sensitivity and glucose timeline — pmc.ncbi.nlm.nih.gov/articles/PMC2726723
Blood pressure and vascular risk — ncbi.nlm.nih.gov/books/NBK9634
SPRINT trial — pmc.ncbi.nlm.nih.gov/articles/PMC4689591/
Blood-pressure lowering meta-analysis — pmc.ncbi.nlm.nih.gov/articles/PMC5308879
Blood pressure and life expectancy cohort — zhgxyzz.xml-journal.net
Lp(a) thresholds — pmc.ncbi.nlm.nih.gov/articles/PMC10531345
Lp(a) and cardiovascular risk — academic.oup.com/eurjpc
Lp(a) and heart attack risk — pmc.ncbi.nlm.nih.gov/articles/PMC11836235
HRV and first cardiovascular event — pubmed.ncbi.nlm.nih.gov/23370966/
HRV meta-analysis in cardiovascular disease — pubmed.ncbi.nlm.nih.gov/31558032/
Body fat and mortality, NHANES — journals.plos.org
Visceral versus subcutaneous fat meta-analysis — nature.com
Visceral fat by sex and mortality — pmc.ncbi.nlm.nih.gov/articles/PMC9891960/
Body-fat thresholds, Annals of Family Medicine 2025 — pmc.ncbi.nlm.nih.gov/articles/PMC12306999
Low body fat and mortality — pmc.ncbi.nlm.nih.gov/articles/PMC3367099
Visceral fat in women, AGES-Reykjavik — pmc.ncbi.nlm.nih.gov/articles/PMC4758353
Normal-weight central obesity in women — pmc.ncbi.nlm.nih.gov/articles/PMC6659146
Cardiorespiratory fitness and mortality — jamanetwork.com/journals/jamanetworkopen/fullarticle/2707428
Fitness MET increments and mortality — clinmedjournals.org
VO2 max decline and mortality — pubmed.ncbi.nlm.nih.gov/27444976
Grip strength meta-analysis — pubmed.ncbi.nlm.nih.gov/28549705
Grip strength and blood pressure, PURE — nature.com/articles/nrcardio.2015.84
Three-night sleep restriction — pmc.ncbi.nlm.nih.gov/articles/PMC5557027
One-week sleep restriction — pmc.ncbi.nlm.nih.gov/articles/PMC2927933
Five-night sleep restriction — niddk.nih.gov
Sleep duration and mortality — academic.oup.com/sleep
Healthy sleep habits and life expectancy — academic.oup.com/qjmed/article/117/3/177/7311739
The 7:1 rule — health.yahoo.com
Legumes and mortality — pmc.ncbi.nlm.nih.gov/articles/PMC10103007
Fiber and mortality — academic.oup.com/aje
Protein intake in older adults — pmc.ncbi.nlm.nih.gov/articles/PMC10413626
Ultra-processed food and mortality — pmc.ncbi.nlm.nih.gov/articles/PMC11874696
Sugar-sweetened beverages and cardiovascular risk — pmc.ncbi.nlm.nih.gov/articles/PMC8402166
Stanford FeFiFo trial — med.stanford.edu
Inflammatory protein changes — healthrising.org
Fiber versus fermented foods follow-up — research.vu.nl

Contact Us

Connect with us and tell us how we can help as you begin on your path towards improved health!