What Is Diastolic Blood Pressure?
Diastolic blood pressure — the bottom number in a reading — measures the pressure in your arteries between heartbeats, while your heart relaxes and refills with blood. It's a key part of your stage classification, not just a supporting figure.
What to know about diastolic pressure
What it measures
The resting pressure in your arteries between heartbeats — the baseline pressure your circulatory system maintains at rest.
What's considered normal
Under the AHA guideline, under 80 mmHg is generally Normal or Elevated (depending on systolic), and 80 or above starts crossing into High ranges.
Why it can matter more in younger adults
Diastolic pressure often carries more weight as a risk indicator earlier in life, before arteries stiffen and systolic pressure takes over as the dominant number.
What a low diastolic reading can mean
A diastolic reading that's unusually low relative to systolic can widen your pulse pressure — worth tracking over time rather than reacting to a single reading.
What Is Diastolic Blood Pressure? — FAQ
What is a dangerously high diastolic reading?
A diastolic reading above 120 mmHg is considered a hypertensive crisis and needs immediate medical attention.
Can systolic and diastolic move in different directions?
Yes — it's common for systolic to rise with age while diastolic stays flat or even drops slightly, which is exactly why CardiLog tracks and charts both separately.
Start tracking today.
Your doctor checks your BP twice a year. CardiLog watches it every day.
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