2 August 2023

Instant tests vs lab-analysed blood tests: Which is better?

Instant tests vs lab-analysed blood tests: Which is better?
Medically reviewed by Dr Leah Gorodi, MBChB, MRCGP, Dip BSLM

With so many at-home tests available at different price points, it can be tricky to understand which test to go for.

To help you make the most of your money and get the answers you need, this article helps distinguish the differences between instant turnaround tests like saliva tests and lab-analysed blood tests.

Which test is more accurate?

The short answer is: it depends on what you’re trying to measure, but in general, lab-analysed blood tests give you more accurate results. Let’s dig into that by looking at a few different conditions.


Usually, when testing for diabetes, doctors look at your blood sugar levels; the amount of ‘glucose’ in your blood. Using a finger prick blood sample is still the most accurate way to determine your risk for diabetes – or manage the condition if you already have it.

This is because glucose levels in your saliva are much lower than in your blood, making it harder to pick up signals of diabetes (1).

Our diabetes test gives you an accurate reading of your average blood sugar levels over the last 3 months. 

Vitamin deficiencies

To check the level of different vitamins in your body, doctors usually look at your blood and analyse a few different markers. This is why lab-analysed finger-prick blood tests are traditionally the best bet.

Although it’s possible to get a rough idea of the level of certain vitamins in your blood from saliva tests, they’re nowhere near as thorough as a finger prick blood sample analysed in a lab and they don’t paint a complete picture (2).

Our advanced vitamin test accurately measures your levels of 3 essential vitamins; vitamin D, vitamin b12 and folate. We also have tests for the individual vitamins if you have a specific concern!

Hormone imbalances

There are many hormones in your body that can be measured in different ways.

Similarly to diabetes and vitamin deficiency testing, most rapid, instant turnaround tests for hormonal imbalances can provide some insight. However, they are far less extensive and can miss out on important markers when compared to lab-analysed blood tests.

For example, it’s possible to take a rapid saliva test to understand levels of certain markers related to thyroid function (3), but to get a thorough understanding of thyroid function, we need to understand levels of specific hormones that we can’t view from saliva.

Our advanced thyroid test provides a comprehensive view of your thyroid function by measuring various directly related hormones and antibodies.

Cost & convenience

In general, if you’re very short on time and want instant results, rapid tests could be the better choice. Plus, rapid turnaround tests are cheaper and quicker on average because the technology used to unpick your results is cheaper and doesn't involve lab analysis.

But, and it’s a big ‘but’, if you’re searching for accurate answers to help you hack your health, rapid tests probably aren’t the best option.

The good news is there’s no need to take time out of your day, or wait weeks for GP appointments or hospital results. All our H&B&Me at-home blood tests give you accurate, doctor-reviewed results within 48 hours!

The final word

Rapid tests can seem appealing because they’re cheap and fast, but they’re much less accurate than lab-analysed blood tests.

Science shows that for most conditions, such as diabetes, vitamin deficiencies, and hormonal imbalances, your blood truly does tell all.

Luckily, H&B&Me blood testing kits provide fast results within 48 hours without compromising on accuracy.


1. Biochip with Graphene-based Nanosensor for Non-invasive Glucose Sensing


2. The Moderate Correlation Between 25(OH)D Serum and Saliva in Healthy People with Low Vitamin D Intake


3) Saliva Iodine Concentration in Children and its Association with Iodine Status and Thyroid Function


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