Guide · Reference
Health metrics guide: lab tests, wearables and more
What you can learn from lab tests, from wearables and from simple measurements — and what each source cannot tell you. A guide to combining health data sensibly.
Written by LON6EVITY Editorial Team · Last updated
Three sources of health data
Laboratory tests measure what is in your blood or urine at one moment. Wearables estimate signals such as heart rate, activity and sleep continuously. Clinical and home measurements — blood pressure, weight, waist, strength — sit in between.
What lab tests do best
Lab tests are the reference for cholesterol, blood sugar, kidney and liver function, blood count, thyroid and vitamins. They are precise but infrequent.
What wearables do best
Wearables show trends: resting heart rate, heart rate variability, activity, sleep duration and estimated fitness. Most features are designed for wellness, not diagnosis, and accuracy varies by device and metric. Some specific functions, such as certain ECG and irregular rhythm features, are cleared by regulators for defined uses.
Combining them
The most useful picture comes from trends across all three: for example rising resting heart rate with worsening sleep, or improving fitness alongside falling blood pressure. Any worrying single value — from a lab or a device — should be checked with a clinician.
Factors that can affect the result
- Measurement accuracy
- Consistency of timing
- Device model
- Laboratory method
Questions people commonly ask
- Can a wearable replace blood tests?
- No. Wearables do not measure cholesterol, blood sugar (unless a dedicated glucose sensor is used), kidney or liver function.
- Which wearable metric matters most?
- Cardiorespiratory fitness and daily activity have some of the strongest evidence linking them to long-term health.
Related topics
Build your longevity profile
What does this mean for your own health data? Log your results, follow trends over time and bring an organised summary to your next doctor's appointment.
Sources
- Physical activity — fact sheet. World Health Organization.
- Cardiorespiratory fitness as a quantitative predictor of all-cause mortality and cardiovascular events in healthy men and women. Kodama S et al., JAMA, 2009.
- Importance of Assessing Cardiorespiratory Fitness in Clinical Practice: A Case for Fitness as a Clinical Vital Sign. Ross R et al., American Heart Association, Circulation, 2016.