Facebook icon

Diabetes Qualified

Measuring blood pressure at home 

Measuring blood pressure at home 

Many people with diabetes also have high blood pressure. If your client has been advised by their GP to check their blood pressure regularly at home you may like to share the below information. 

By Carolien Koreneff, Registered Nurse and Credentialled Diabetes Educator

What is blood pressure? 

Blood pressure is the measurement of the pressure of the blood in the artery. As your heart pumps blood out into the arteries, the blood pushes against the artery walls, creating a pressure. This pressure will change throughout the day, as it depends on a number of factors, including: 

  • How much fluid is in your body 
  • What you are doing when measuring your blood pressure 
  • Any medications you may have taken 

High blood pressure is known as hypertension, it is a condition where your blood pressure is constantly elevated.  

How to check blood pressure accurately 

  1. Avoid eating, drinking caffeinated drinks, exercise and smoking for 30 minutes before taking a reading, as these can elevate your blood pressure.  
  2. Empty your bladder first. Having a full bladder can mean you are less relaxed, and hence can increase your blood pressure. 
  3. To be able to compare readings, it is often recommended to check your blood pressure at the same time every day, when it is convenient for you. It is also recommended to use the same arm each time (though it does not matter which arm you choose). 
  4. Only use validated machines. Finger and wrist blood pressure devices are not all that accurate and are not recommended. 
  5. Sit quietly for five minutes before taking your reading. Talking and moving both affect accuracy, so it is important to avoid these.  
  6. Sit in a relaxed position, with both feet flat on the floor. Make sure that your legs are not crossed and your back and arm are supported.  
  7. The cuff should be at the level of your heart. Putting a pillow on the table under your arm can help you achieve this. Having your arm too low can falsely increase your blood pressure. Having your arm too high, above your heart level, can lead to a lower than accurate blood pressure reading. 
  8. Use a cuff that fits properly around the top half of your arm. Most people can use a standard size cuff (12x35cms). If the cuff is too big, the reading will be falsely low. If the cuff is too small, the reading will be falsely high. You know you have the right size, if the bladder inside the cuff encircles 80% of the top of your arm. 
  9. Place the cuff on bare skin, or over thin, loose fabric. If the fabric is thick or tight, it is better to take your arm out of the sleeve, rather than rolling up your sleeve. 
  10. The cuff should be placed 2-3cm above your elbow joint. Most cuffs have markings on them, that ensure that the centre of the bladder in the cuff is positioned in line with your artery. 
  11. Once you are in the right position, with the blood pressure cuff in the right place, turn the monitor on and press “start”.  

The first reading is often elevated, as your body gets a bit of a shock due to the sudden tightness around your arm. It is therefore recommended to check your blood pressure again after a couple of minutes. 

Write down the numbers exactly as they appear on the screen. This includes both the systolic (the higher number) and diastolic (the lower number), and in some cases your pulse rate.  

Choosing a blood pressure monitor 

When buying a blood pressure monitor there are a few points to consider. 

Firstly, the cuff size. Most people can use a standard size cuff (12x35cms), but poor fitting cuffs will not give an accurate reading. Check with your healthcare professional to determine what size cuff would be best for you to use.  

Secondly, consider the device itself. Does the display show the measurements clearly? Is it easy to read? 

Lastly, there is the cost. Some monitors are more expensive than others. More expensive does not necessarily mean that the monitor is more accurate. It may be worthwhile to check with your private health insurance provider if they can cover the cost of the monitor. 

It is important to regularly check the accuracy of the device. The easiest way to do this, is to bring it with you on one of your GP visits, and to compare the reading to that taken by your doctor. Yearly checks of your monitor should be sufficient. 


For most people with diabetes, it is recommended to aim for a blood pressure target of less than 145/80 millimetres of mercury (mmHg).  

Your doctor may recommend a different target, based on your specific circumstances. If so, that is of course the target to aim for. 

If you experience any symptoms, such as dizziness or fainting, even if your blood pressure is in your target range, see your doctor. 

If your blood pressure is above 180 mmHg systolic (the higher number) or above 120 mmHg diastolic (the lower number), wait 5 minutes and check it again. If your readings are still high, contact your doctor for advice. If your blood pressure is above 180/120 mmHg and you experience chest pains, shortness of breath, changes in your vision, weakness, numbness or difficulty speaking, call 000 immediately! 

Studies have shown that there can be a difference of around 10 mmHg pressure between the right and left arms. Any difference less than 10 mmHg is considered normal and not a cause for concern. 

Special considerations 

People with arrhythmias (irregular heartbeats, for example those with Atrial Fibrillation or AF) should go to the doctor to get their blood pressure checked, as digital devices are not accurate in this situation. 

Women who have had a mastectomy (the removal of a breast, generally due to cancer) may be at risk of developing lymphoedema, if lymph nodes were removed during the surgery. To minimise the risk of developing lymphoedema (permanent fluid build-up in the skin due to a restricted flow of fluid which causes localised swelling) it is recommended to not check your blood pressure on that side. 

If you have any questions or concerns regarding the content of this article, please call the NDSS Helpline on 1800 637 700 to speak with a health professional, or visit the Heart Foundation. For additional resources on heart health, including factsheets, action plans and a free recipe book, head to takediabetes2heart.com.au.