Know Your Numbers: The Values That Protect Your Heart

"Know Your Numbers" means knowing your own blood pressure, blood lipids, blood sugar and body weight. These factors usually cause no symptoms for years, yet they strongly shape your risk of heart attack and stroke ¹. The encouraging part: all four are easy to measure, and each one can be improved. What matters most is turning a single number into a trend you can actually work with.

The scale of the opportunity is striking. Cardiovascular disease is the leading cause of death worldwide and accounted for roughly one in three deaths in 2022 ¹. At the same time, most of it is considered preventable when risk factors are spotted early and addressed ¹.

What does "Know Your Numbers" actually mean?

"Know Your Numbers" is a guiding principle of cardiovascular prevention rather than a single programme. The idea is simple: everyone should know a few key health values about themselves, as naturally as they know their shoe size.

The clearest scientific framework behind it comes from the American Heart Association, which calls it Life's Essential 8 ³. It defines heart health through eight building blocks: four behaviours (diet, physical activity, avoiding nicotine, sleep) and four measurable health factors – blood pressure, blood lipids, blood sugar and body mass index (BMI) ³. Those four measurable values are "the numbers". As a minimum, the AHA recommends checking them in adults at least every five years ³ – a long window for values that can shift with everyday habits.

Why can't you feel when these values are too high?

Because the damage builds up quietly and sends no warning signals for a long time. Think of your blood vessels as a network of pipes: if it runs under too much pressure for years, or fat builds up along its walls, it wears down – without you noticing anything.

The WHO describes exactly this pattern: the underlying disease of the blood vessels often causes no symptoms, and a heart attack or stroke may be the first sign ¹. Raised blood pressure, blood sugar and blood lipids, however, can be measured and signal increased risk long before anything happens ¹.

Your body may not warn you. A measurement can.

How many people don't know their blood pressure?

Surprisingly many. The largest analysis of global blood pressure data to date pooled more than 1,200 population-representative studies. It found that in 2019, around 580 million adults aged 30 to 79 had high blood pressure without knowing it – 41% of affected women and 51% of affected men ². High blood pressure was defined as 140/90 mmHg or above ².

The gap is rarely about medical knowledge. Most often, nobody ever measured. The same analysis shows it doesn't have to be this way: in countries such as South Korea, Canada and Iceland, more than 70% of people with high blood pressure were being treated in 2019 ². Detecting and acting is not a distant ideal – it simply needs structures that make it routine.

Which values are considered healthy?

For people without known cardiovascular disease, there are clear reference ranges:

Value	What it shows	Healthy range	How it's measured
Blood pressure	pressure in your arteries	below 120/80 mmHg 3	upper-arm monitor, pharmacy, GP
Non-HDL cholesterol	all cholesterol fractions that can burden your arteries	below 130 mg/dL (about 3.4 mmol/L) 3	blood test
HbA1c (long-term blood sugar)	average blood sugar over the past 2–3 months	below 5.7% (39 mmol/mol) 3	blood test
BMI	weight relative to height	below 25 kg/m² 3	scale and tape measure

One important caveat: these are reference ranges for healthy people, not treatment targets. The European cardiology guideline (ESC 2024), for example, sorts blood pressure into three groups: non-elevated (below 120/70 mmHg), elevated (120–139/70–89 mmHg) and hypertension (140/90 mmHg or above) ⁴. People already on treatment often have a different goal – the ESC usually recommends an upper value of 120 to 129 mmHg, if well tolerated ⁴. Cholesterol targets likewise depend on a person's overall risk.

The table hides one more thing: a single value is a snapshot. Whether an HbA1c of 5.6% is stable or has been creeping up for two years makes a real difference – and you can only see that over time.

Does knowing your numbers actually make a difference?

Yes – but only when the number leads to a next step. The research is remarkably clear on this.

A large Cochrane review analysed 17 randomised trials of general health checks in adults without known disease. It found that the checks on their own had little or no effect on overall mortality or cardiovascular deaths ⁶. Among the possible reasons, the authors note that people at the highest risk are less likely to attend, and recommended follow-up steps are not always taken ⁶.

That's not an argument against measuring – it's an argument against measuring without consequences. What reliably works is what happens next. An analysis of 48 randomised trials with around 345,000 participants showed that every 5 mmHg reduction in the upper blood pressure value lowered the risk of major cardiovascular events by about 10% ⁵ – including in people without prior heart disease and with starting values previously considered normal ⁵.

So the gap isn't knowledge. It sits between the measurement and the change. A one-off result that ends up in a drawer protects no one.

What could prevention look like if we took our numbers into our own hands?

For most people today, prevention is a rare event: a check-up every few years, a lab report on paper, maybe a short conversation. Whether anything changes afterwards usually stays invisible – to doctors and to ourselves.

We believe prevention can look different. Imagine knowing your values not just once, but following them over time. You notice when a value starts drifting in the wrong direction – long before it becomes a problem. You know which everyday change can influence exactly that value. And at your next measurement, you see whether it worked. A passive check-up becomes a process you steer yourself.

That is our approach at speak23. Instead of a one-off snapshot, you measure your blood values two or four times a year. Every result is recorded digitally and automatically, so your history, trends and changes are visible at a glance in the app. Building on that, you receive personalised, evidence-based recommendations designed to steer your trends in the right direction. And the app accompanies you along the way, showing how your actions affect your values.

Whether this approach prevents heart attacks and strokes in the long run is something research still has to show. But it targets precisely the point where, according to the evidence, classic health checks fall short: continuity and the next step.

What can you do in practice?

1. Measure regularly, not just once. With speak23, you check blood values such as cholesterol and HbA1c two or four times a year, turning single numbers into a meaningful trend. Start with the speak23 Core Health blood test.
2. Understand your trends instead of collecting paper. Your results go straight into the app, so you can see whether a value is stable, improving or slowly getting worse.
3. Work on the big levers – in a targeted way. Quitting tobacco, eating less salt, more fruit and vegetables, regular physical activity and limiting alcohol have all been shown to lower cardiovascular risk ¹. The personalised recommendations in the app show you which of these matter most for your values right now.
4. See the effect. At your next measurement, the app shows how your changes have affected your values – making progress tangible and helping you stay on track.
5. Check your blood pressure as well. Blood pressure isn't a blood value, so no blood test can measure it. Check it regularly, for example with an upper-arm monitor at home; and save them regularly in the speak23 platform to see trends. The ESC explicitly recommends such readings to confirm elevated values ⁴. Look at it together with your blood values – only together do they show the full picture.
6. Get unusual values checked by a doctor. speak23 does not replace a diagnosis. If a value falls outside the healthy range or shows a clear trend, discuss it with your doctor – your documented history is a valuable basis for that conversation.

Why does this matter so much right now?

Because the challenge is shifting. The number of people with high blood pressure has doubled since 1990 to around 1.28 billion, largely because the world's population is growing and ageing ². As we live longer, the question is no longer just how many years we live, but how many of them we spend in good health.

Medicine is rethinking its role: away from repairing things once they break, towards looking early and staying alongside people. We believe this shift doesn't only happen in hospitals, but with every person who takes responsibility for their own numbers.

Perhaps the most important number, then, isn't your blood pressure or your cholesterol. It's the number of measurements you learn from.