Which blood tests to get, and when to start
September 29, 2026 · 23 min read
Casey Means, Sara Gottfried, Kyle Gillett and Peter Attia each lay out biomarkers worth tracking by age and sex, from glucose and insulin to hormones and lipids. Starting a baseline early lets you catch drift years before disease.
The rules, numbers and steps worth keeping in front of you.
- When to start: as early as possible, before symptoms, to learn your own normal.
- Casey Means's seven: fasting glucose, triglycerides, HDL, A1c, total cholesterol to HDL, waist, blood pressure.
- Her cutoffs: glucose under 100, triglycerides under 150, A1c under 5.7 percent, pressure under 120/80.
- Useful extras: fasting insulin, HOMA-IR, ApoB, hs-CRP, uric acid, GGT.
- Read markers together; high-normal glucose plus high-normal triglycerides suggests insulin resistance.
- Sara Gottfried: women should baseline estrogen, progesterone and testosterone in their 20s or 30s.
- Time the draw to day 21 or 22 of a 28-day cycle, earlier as cycles shorten.
- Gottfried: insulin can change years before glucose does.
- Kyle Gillett: men need testosterone with SHBG or free testosterone, not total alone.
- Free testosterone is roughly 2 percent of total as a rule of thumb.
- Peter Attia: apoB is the key heart marker; test lipoprotein(a) once.
- Attia: bloodwork is weak for cancer risk; add DEXA and VO2 max.
- David Sinclair: track HbA1c, hs-CRP and iron against your own history.
- Retest about every six months, and have a qualified physician interpret results before acting.
This is the short form. The full insight has every expert's reasoning, their own words and the sources.