GD PICS 108Why are we testing and monitoring blood sugar levels?

Anyone diagnosed with gestational diabetes should regularly test their blood sugar levels.

Sometimes ladies that are higher risk or classed as borderline, or those that have had gestational diabetes in previous pregnancies may also be advised to test and monitor levels.  This is the best way to see what is happening with your blood sugar levels and how much glucose is remaining in your blood after eating and therefore being passed on to your baby.

It’s just a guide

These capillary tests are a ‘guideline’ only and not 100% accurate.  The only way to get an accurate blood glucose test result is from a blood test which has been analysed in a sterile laboratory environment.  Therefore if you test multiple fingers, one after another, you could get different readings each time.  Many ladies get frustrated when they hear this and think what is the point if the tests are not 100%, but for a mobile device they do a pretty good job of building up a good picture as to what’s happening and a guide is much better than not be aware at all. If you feel there are any inaccuracies with your test monitor then please consult your healthcare professional. Large differences in readings may mean that your machine is faulty or could need calibrating.


Test times and targets

bs levels book moreDifferent test times and targets are used all across the UK and Ireland, even a hospital a few miles away may have different guidance to yours. Please follow the guidance YOU have been given from your diabetes team/consultant and medical professionals.  You may wish to take additional tests, but it important to provide your diabetes team with the information they require.  Here are some examples of test times used:

  • one hour post meals
  • two hours post meals
  • pre meals
  • pre meals and one hour post meals
  • alternating days between pre and post meals
  • random testing so many times a day or week

many areas will also ask for fasting levels, which should be taken once waking in the morning and others may ask for readings before bed too.

NICE guidelines (England & Wales)  for testing blood sugar levels:

1.3.2 Advise pregnant women with type 2 diabetes or gestational diabetes who are on a multiple daily insulin injection regimen to test their fasting, pre‑meal, 1‑hour post‑meal and bedtime blood glucose levels daily during pregnancy. [new 2015]

1.3.3 Advise pregnant women with type 2 diabetes or gestational diabetes to test their fasting and 1‑hour post‑meal blood glucose levels daily during pregnancy if they are:

  • on diet and exercise therapy or
  • taking oral therapy (with or without diet and exercise therapy) or single‑dose intermediate‑acting or long‑acting insulin. [new 2015]



Test from first or last bite?

A common question we’re asked is “do I test post meal levels from the first bite or last bite when eating?”  You must ask your team which they prefer as this guidance differs.  Some diabetes clinics may say that it doesn’t matter, if this is the case then decide which is better for you and stick to that for your test times to give consistency in readings. The majority of ladies find testing from last bite easier, especially if you are planning on dining for a longer period of time at any point, rather than a quick meal or snack.


Our thoughts on testing blood sugar levels

Even if you have been advised to test only pre meals, 2 hours after meals or alternate testing times on different days etc. our thought remains the same. Research suggests that testing post meals is beneficial to controlling gestational diabetes

  • In order to build up a good picture, you could test at your advised times, but also test one hour after all meals.  This way you can build up a picture and understand what foods you can tolerate.  If you do not test after food then you may not see if foods are raising your blood sugar levels high.

Macronutrients impact on blood glucose


NICE levels2

If you don’t have one hour post meal test target, then a good guide to go by are the NICE recommendations for testing which are <7.8mmol/L after one hour.

If you want to also test at two hours post meals, the NICE recommendations are <6.4mmol/L.

Please note:  Only you can make the decision as to whether you wish to take additional tests, but many ladies have found this advice has helped a great deal in understanding what foods and drinks they can or cannot tolerate.



  • Keep a food diary so that you can build a picture of what you can and can’t tolerate and can refer back to.
  • Test one hour after snacks. This is a helpful way of understanding what snacks you can tolerate.  You may want to do this at the beginning until you have a good understanding of what you can tolerate and then only test after new snacks in the future.
  • Once you have your blood sugar levels under good control you may want to try out some GD friendly treats. These are things that you wouldn’t eat on a daily basis but would be nice as treat every so often, such as some strawberries and cream, half a wholemeal scone with clotted cream or some dark chocolate and nuts. Our thoughts on testing after things that you feel may push your levels higher than your known safe foods, is to test more frequently to see how you react and avoid extreme highs. Some ladies like to test after 15 mins, 30 mins just to gauge the effect. Research suggests that continuous blood glucose monitoring is beneficial to all diabetics. In fact many of our group members have been involved in continuous blood sugar monitoring research where an implant testing device is used to continually monitor levels. Unfortunately this is not something that is yet being offered to mothers with gestational diabetes, but is something that would be very beneficial for detecting both hypers and hypos. If blood sugar levels cannot be continuously monitored then some extra tests may help you understand what’s happening. Whilst all people’s blood sugar levels will raise after eating, you may wish to find out of you are eating things which are raising your levels to a very high extent and avoid these things to opt for safer foods which keep your levels stabilised and controlled. Overall stabilised, controlled blood sugar levels help towards preventing complications caused by gestational diabetes.


Testing blood sugar levels

It is best to ask your healthcare professional to show you how to use your testing equipment. You should be shown how to use your blood glucose monitor and take a test at hospital, however many ladies feel overwhelmed and concerned over testing and some really struggle to take the first few tests alone at home.

Here’s a basic guide as to what to do, but please bear in mind that not all blood glucose meters are the same, so you may need to slightly modify the method detailed below.

For testing your blood sugar levels, you will need:
  • a blood glucose meterGD PICS 116
  • a test strip
  • a lancing device
  • your testing book if your are required to record your readings

Some blood glucose meters may come with test strips and/or lancing devices, others will have them all separate.  Ideally you will also be given a sharps bin to dispose of your used lancets, however some areas do not give these out.  It is worth asking for one as many GPs will happily add this onto your repeat prescription, along with all your other things and you only need one small sharps bin that can be used for a long time.  If you are not given a sharps bin, ask your diabetic team how you should be disposing of your lancets.

How to test…

 Prepare your kit ready for testing blood sugar levels:

This should include: your meter, a test strip to hand (have some spare strips to hand too), the lancing device (finger pricker), cotton wool or tissue (optional) and a monitoring diary to record the results 

  1. Ensure that the finger pricking device has been loaded with a new lancet – many clinics will advise you mayGD PICS 158 use the same lancet multiple times through the day/week.  Your fingers will suffer tremendously if you do this! A lancet that has been used numerous times becomes blunt and therefore will hurt you much more.  You’re going to be testing A LOT anyway, so look after those fingers!  Once the lancet is loaded and the device cap is replaced, pull back the spring device to load the lancet ready for use.

  2. Wash and dry your hands – to ensure that the result is not influenced by any sugars that may be present on your fingers, even touching your hair can give a false high reading!   After using soap, wash thoroughly in just water as most soap and hand sanitisers (even antibacterial ones) can cause false high readings due to ingredients found in the products and the residue left on your skin.  A fuller drop of blood will be obtained if your fingers are warm, so it’s worth warming your hands by washing them in hot water if you can.

  3. Put a test strip into your meter.  This turns many devices on and many ‘beep’ once the test strip is inserted, showing it is ready for use.

    GD PICS 160

  4. Check the depth setting on your lancet device is not too high and prick your finger.  Aim for the side of the finger (just under the edge of the nail) as there are less nerve endings here than at the tips or the ‘pads’ of the fingers where your finger prints are.  Avoid the thumb and forefinger for testing as repeat testing can cause loss of sensitivity in those areas of your fingers.  NB.  You may need to squeeze your finger a little until blood appears – if you find you need to squeeze hard, try pricking a finger again.  If it’s hurting too much when pricking your finger, then lower the setting on the lancet device.

  5. When blood appears, check the meter is ready and then transfer the blood onto the test strip (some diabetes teams will advise wiping away the first drop of blood and squeezing the finger for the next drop of blood to transfer onto the test strip).  This is the tricky bit that many struggle with, as many monitors will show an error code if not enough blood is applied to the test strip and do not allow you to re-use the test strip.  Ideally you need a droplet the size as shown in the picture above and you need to hold your finger in place while the test strip absorbs or ‘sucks up’ most of the blood.GD PICS 114

  6. Wait a few seconds – most meters provide a result within 10 seconds and often sooner.



  • If the test is unsuccessful, repeat the whole process again
  • If the test is successful, clean any blood off your finger – with the cotton wool/tissue if necessary
  • Record the result in your blood glucose monitoring diary
  • Dispose of the test strip and lancet, ideally into a sharps bin





Unexpected or strange readings (higher or lower than expected)

If you test and get an unexpected high or low, then follow the steps again and retest to check the result, but ALWAYS wash your hand in just water before testing. Write down all results in your monitoring diary with any explanations for repeat testing.  Give your diabetes team a call if you are concerned over any of your readings.


GD PICS 118What is a high reading?

We class a high reading (or ‘spike’) a level which is higher than your top target. So if your target is <7.8mmol/L one hour after eating, 7.9mmol/L is a high reading as it is above your target. If you have a range e.g. 6.0-8.0mmol/L after meals, then 8.1mmol/L is classed as a high reading.


How low is too low?

A question that we get asked frequently get asked in our Facebook support group, is how low is too low? The answer to this question differs depending on how your gestational diabetes is controlled:

  • If you are taking Glibenclamide or Insulin to help control your blood sugar levels (at any point in the day) then levels below 4.0mmol/L are classed as low, a good phrase to remember is “four is the floor”.  As Glibenclamide is a sulfonylureas medicine it can cause hypoglycaemia (hypos), the same as insulin. Please note: some medical teams may advise that a hypo is a blood sugar level below 3.5mmol/L rather than 4.0mmol/L.
  • If you are controlling your blood sugar levels with dietary changes alone or with Metformin then you cannot have a a true hypo.  You may experience low levels and have hypo type symptoms, but there is no need to treat the hypo with glucose to raise levels.  Eating a normal, gestational diabetes suitable snack will raise levels enough and should make you feel better. This is known as a ‘false hypo’. For more information on false hypos, please read more here


Ladies often get concerned when their levels are below or towards the lower end of their test target range, but this is not a cause of concern unless levels are extremely low i.e. if your target level is to be 5.3mmol/L for your morning fasting level and get a levels in the range of 4.0-5.2mmol/L this is fine, it’s actually a good thing!


Levels dropping after eating?!

A commonly asked question in our Facebook support group is why have my levels dropped after eating?  99% of the time when we ask what they’ve eaten they will say that they have eaten a meal without any starchy carbohydrates. Meals that are made up of high protein will very often result in levels lower than the pre-meal test and example of this recently was a meal of chicken breast and salad. Whilst you may think horray! …a great way to get lower levels, beware.  Carbohydrates should be eaten at every meal to give energy and to prevent ketosis.

For more information on low blood sugar levels, take a look at this post.

Research links

Different techniques of blood glucose monitoring in women with gestational diabetes for improving maternal and infant health

There is evidence suggesting that more regular and frequent testing for glucose levels is associated with improved outcomes.

Postprandial versus Preprandial Blood Glucose Monitoring in Women with Gestational Diabetes Mellitus Requiring Insulin Therapy

Continuous Glucose Monitoring

Clinical use of continuous glucose monitoring system in gestational diabetes mellitus and type 2 diabetes complicated with pregnancy

Continuous glucose monitoring effects on maternal glycemic control and pregnancy outcomes in patients with gestational diabetes mellitus: a prospective cohort study