Are you missing the spike?

Could you be missing the spike in your blood sugar levels?

A spike in blood sugar levels is the highest peak your blood sugar levels reach after eating or drinking. But could you be missing the spike? Depending on your test times, then you could be missing the spike and depending on your target level it can be confusing what is deemed as a spike or high level.

spike in blood glucose UKWhen excess glucose in the bloodstream passes through to the baby it causes excessive growth and other possible related complications. Targets for measuring blood glucose are given and being below that target level is deemed as being a safer level for fetal growth, minimising the risks associated with diabetes in pregnancy.

There has been uncertainty if it is the overall glucose control or the spikes in blood sugar levels that influence the baby’s growth but the HAPO (Hyperglycemia and Adverse Pregnancy Outcomes) 2008 study suggests that both fasting and postprandial glucose levels influence fetal growth and so this is why the majority of ladies will be testing both fasting levels and pre or post meal levels.



How do you know when to test your blood sugar levels and at what time?

bs levels bookYou get diagnosed with gestational diabetes. You go to your hospital appointment, get given a blood glucose test monitor, shown how to use it and then you’re given your test times and targets. But this is where it can be VERY confusing, especially when you compare your targets with mothers from other hospitals…

Although there are National guideline recommendations which are backed by research as to what targets should be used for the best outcomes with gestational diabetes, hospitals and Trusts do not have to follow them. This means that ladies in the UK & ROI can be given all sorts of different blood glucose monitoring targets and test times. Some may be very strict, others can be very lenient. You could literally go to one hospital and be given one set of targets and tests times and the next hospital a few miles away could be dramatically different.

So where does that leave us? We have two options:-

  1. Follow the guidance set by your hospital, trusting that as your medical professionals they know the best for your gestational diabetes pregnancy and only test at those set times with the targets given
  2. You could research the subject a bit further and make your own decision based on what you find out and what you are happy to do. We would not and cannot advise you to go against the advice from your medical professionals, BUT there is nothing stopping you from discussing your test targets and times with them and/or doing additional testing if you wish


Any testing is better than no testing

diagnosed with gestational diabetesFirstly we should point out that any blood glucose monitoring is better than no monitoring at all. Capillary blood glucose monitoring is just a guideline, but it will help build up a good picture as to what is happening in your body.

That said, when you test and the targets used can also make a huge impact on how your gestational diabetes is managed and controlled.

The more you test, the more you can see and build a much bigger picture. You can learn which foods you struggle with and tweak meals accordingly. Taking this approach can mean that you stay diet controlled for longer, or lower amounts of medication or insulin are required.


Looking at the most widely used testing targets – the postcode lottery

NICE guidelines are recommended guidelines for England, Wales and Northern Ireland in parts (launched 2015). NICE advises testing fasting and 1-hour post meal levels for diet and metformin controlled women, plus additional pre-meal and bedtime monitoring for those on multiple daily insulin injections. The NICE targets for testing are:-

  • NICE levels for gestational diabetesfasting: 5.3 mmol/litre
  • 1 hour after meals: 7.8 mmol/litre or 2 hours after meals: 6.4 mmol/litre

SIGN guidelines are recommended in Scotland (launched 2013). The SIGN guidelines do not recommend targets in their guide but do mention at what levels to treat with glucose lowering therapy and so we can only take from that information. SIGN have 2 different target guidelines, depending on gestation:-

  • Before 35 weeks: <5.5 mmol/l pre-meals or <7 mmol/l two hours post-meals
  • Over 35 weeks: <5.5 mmol/l pre-meals or <8 mmol/l two hours post-meals

HSE guidelines are recommended in Republic of Ireland (launched 2010). HSE recommend testing fasting and 1-hour post meals:-

  • Fasting capillary glucose level: 3.5 – 5.0mmol/L
  • 1 hour post-meals capillary glucose level: <7.0mmol/L


Straight away you can see that within the 3 biggest guidelines we have a big difference in guidance, with HSE guidelines being more strict, NICE in the middle and Scotland being much more lenient.


Who provides the ‘best’ targets and test times?

Where do we go from here in the knowledge that these 3 recognised guidelines all differ? All the guidelines are based on research, but the NICE diabetes in pregnancy guidelines were completely reviewed and updated based on the most recent research on 25th February 2015 and they provide vast amounts of evidence to back up the recommendations used. You can read all the evidence in full.

questionsTo give you an idea of the range of test targets used, we have seen ladies in our support group being advised to aim for post-meal targets of <6.0mmol/l after one hour, up to the highest recommendation of being <10.0mmol/l after two hours! Test times vary from testing as little as once a week, to testing 7 times a day!

With all this in mind, we feel NICE provides the most up-to-date and beneficial advice. The Irish guidelines are strict in comparison, which makes achieving those levels harder and may leave some ladies struggling with hypoglycaemia. As far as impacting fetal growth, which is the aim of the task at hand, then our bigger concern is around those following targets higher than the NICE recommendations.


What we have seen in our support group

With so many different targets and test times being followed by our members in our support group, we notice that it is very often that the ladies who seem to be able to ‘tolerate more’, are those testing at 2 hours post-meals, testing only pre-meals, or only sporadic or random testing (not testing the same times daily). They can often be the ladies commenting that they can tolerate higher amounts of carbs such as breakfast cereals, jam on toast, orange juice and sweet treats, but there is a concern that they are missing their spikes in blood sugar levels.

Those that are testing fasting and one hour levels seem to be able to tolerate less, have to be a bit more restrictive and we believe are therefore not missing the spike in blood sugar levels as much as others.

We also see comments where ladies are experiencing hyper type symptoms not long after eating, yet are getting within target levels when it comes to completing their 2 hour test or pre-meal test, suggesting they may have missed a spike in their blood sugar levels.

Gestational Diabetes UK Facebook groupAnother common post is around estimated fetal weights and high growth plotted on centile charts. We see ladies saying that their team cannot understand why when their tests are showing good blood glucose control, yet their baby is still showing signs of accelerated growth. We believe test targets and times can play a big part in this, because if the targets used are high targets or late testing times, then the spikes in blood sugar levels may be missed, therefore the gestational diabetes may not be as well controlled as it could be.

Testing times versus the food eaten

When you test plays a big part in the readings you get and what you will be able to tolerate. This is because of the length of time food and drink takes to convert to glucose in the bloodstream…

90 – 100% of carbohydrates turn into glucose within 1 – 2 hours.  Whereas with proteins and fats, much less turn into glucose and over a much longer period of time:-

Macronutrients impact on blood glucose


Do spikes in blood glucose levels matter?

missing the spikeWhen we eat or drink most things our blood sugar levels rise, this signals to our pancreas to release insulin which processes the glucose and gives us energy. With diabetes we may not be able to produce enough insulin, or we may not be able to use the insulin that we produce, well enough and so our blood glucose levels can remain high.

Another problem we see with many ladies is erratic blood sugar levels, suggesting that they are suffering from spikes and crashes, which leads to roller coaster levels.

Sometimes, if a high carb load is eaten or drunk, meaning high amounts of sugar such as full sugar drinks, cereals, cakes, sweets and white flour pastries etc, the pancreas may overproduce insulin and blood sugar levels can crash fairly low following eating, yet it can give the false impression that the high carb food or drink is tolerable.

spike and crash

As long as my levels are under my target at my test time then everything is fine, right?

missing the spike
Lucky or has this Mum missed the spike???

If you’ve read this whole article to this point then you will see the answer heavily relies on your test times and targets you’ve been given to follow and how well you are managing to control the growth of your baby/babies.

The majority of healthcare professionals will advise that all peoples blood sugar levels raise after eating but as long as your levels drop to below your target level at your test time then this is fine and so they advise that additional tests are not necessary. But I’m not sure what their opinions would be if they saw some of the posts we have seen where ladies have admitted to eating things that we know are not good for gestational diabetes, such as the image I’ve shared here.

We have found that additional testing has been hugely beneficial in managing gestational diabetes which results in more ladies remaining diet controlled, or ladies being on much less medication or insulin.

You need to provide your healthcare professionals with the information they require BUT if you wish to discuss your test times or targets, or wish to test more then you should.


Additional testing within the hour to monitor the spike

We have learnt that the more we test, the more we are able to see how well our body is reacting to foods and drinks. Which in turn means that diet control can be achieved for longer, or less medication or insulin is required.

Continuous blood sugar level monitoring, where a testing device is implanted and automatically tests blood sugar levels every 15 mins is something that is hugely beneficial to diabetics, but there is little research in pregnant ladies with gestational diabetes. There are currently research trials being conducted on this, but we feel that we are a long way from this method of monitoring is used with all patients.

blood sugar rollercoaster1
picture credit to Connie Bennett and Isabella Bannerman at

In the knowledge that certain foods and drinks can spike blood sugar levels extremely high within as soon as 15 minutes, some ladies in our support group like to test more frequently to see how their body reacts to certain things, testing at 15, 30, 60, 90 and 120 minutes. They then tweak or avoid certain things depending on the levels recorded.

There are no targets available for testing with this method and so many ladies stick to NICE guideline of aiming to stay below 7.8mmol/l and below 6.4mmol/l after 2 hours.

Obviously it is highly impractical to test like this after everything eaten or drunk and we do not recommend this, but it is particularly handy when wanting to try something that you feel may push your blood sugar level boundaries and spike you very high, such as a treat.

We aim to support ladies in gaining good overall lowered blood sugar levels and not only lower levels, but STABILISED levels, aiming for levels which would look more like rolling hills than huge peaks and troughs if you were to draw a picture.


spike in blood sugar levels

Benefits of an additional 2 hour test for high fat meals

indian buffetWe know that high fat meals can spike blood sugar levels after one hour, especially things like takeaways. This is the one instance where we believe 2 hour testing is beneficial as this slower spike is often detected at this time due to the fat slowing down the release of glucose in the bloodstream.

If having a higher fat meal, then we advocate testing at both one and two hours to see the impact the food has had on blood sugar levels.

If you do not have a 2 hour test target then a level of <6.4mmol/l after 2 hours is the target recommended by NICE.


Benefits of testing after snacks

chocolate and gestational diabetesYou will not be advised to test after snacks, you may be advised not to have snacks (but I’ll leave that for another post!) We find testing one hour after snacks extremely beneficial in building up the picture of what you can tolerate.

If it is a sweet treat, such as chocolate or a treat like a wholemeal scone with cream, then you may want to test more frequently to check for an earlier spike too.


Advice around stopping testing or reducing testing

thumbs up
you decide and carry on testing if you want

Some ladies are advised to reduce testing or completely stop following good blood sugar level results. Bearing in mind that these ladies have tested positive for gestational diabetes, did have higher levels when not following a good GD diet and in the knowledge that gestational diabetes is a progressive condition which worsens as the pregnancy goes on, then you may want to carry on testing to see how your levels are.

Typically, gestational diabetes worsens from 32-36 weeks and so if you have been advised to reduce or stop testing in this time, you may want to continue for peace of mind.


What NICE found when comparing research data

NICE recognises that fasting and postprandial (post-meal) levels are the most important and are beneficial over preprandial (pre-meal) testing and that preprandial testing should be added in those that take multiple insulin injections a day. They also found the study comparing 1-hour versus 2-hour post prandial testing was of very low evidence.

NICE guidance ng3 evidence full

One hour postprandial versus 2 hour postprandial comparison One study compared 1 hour with 2 hour postprandial testing and provided very low quality evidence of no significant difference in the 2 outcomes examined (caesarean section and large for gestational age). The guideline development group commented on the lack of detail reported in this study regarding the exact timing of testing; notably was it from the beginning or from the end of each meal? The group noted from the review of continuous glucose monitoring that the postprandial peak in glucose is likely to be 60 to 90 minutes after meals, though again it was not clear whether this was from the start or the end of the meal. The group also considered that it may be more convenient and women may be more likely to remember to perform testing if it was performed sooner (at 1 hour) rather than later (2 hours) after the meal finished. Key conclusions The guideline development group concluded that for all women with diabetes both pre- and postprandial testing was important during pregnancy and that it should be performed 7 times a day for women with type 1 or insulin-requiring type 2 or gestational diabetes. Women who achieved glucose regulation using diet or oral therapy or single dose intermediate or long-lasting insulin did not need to test preprandially and testing could be limited to a fasting sample and samples at 1 hour after meals every day

5.2.7 Evidence to recommendations Relative value placed on the outcomes considered The guideline development group prioritised pre-eclampsia and maternal hypoglycaemic episodes for maternal outcomes and large for gestational age and shoulder dystocia for neonatal outcomes. The group noted that data from the HAPO study (HAPO Study Cooperative Research Group et al., 2008) demonstrated a linear relationship between maternal blood glucose and the risk of complications such as macrosomia. Thus, in theory, blood glucose values in women with any form of diabetes should be kept as close to the non-diabetic range as possible. However, the group acknowledged the difficulties of safely achieving this in practice because of the risk of hypoglycaemia. Therefore, in making recommendations about target values for women with diabetes in pregnancy, the group inclined to use those values for which the evidence showed some benefit. Accordingly, from the evidence they suggested that the following would be reasonable targets:  fasting level – less than 5.3 or 5.6 mmol/litre (Rowan et al. [2010] reported a lower incidence of pre-eclampsia and large for gestational age with a target threshold of 5.3 mmol/litre, but Farrag [1987] reported a higher incidence of maternal hypoglycaemic episodes with a target threshold of 5.6 mmol/litre.)  1 hour value – less than 7.8 mmol/litre (In a study of women who largely measured the 1 hour values, Combs et al. [1992] reported a lower incidence of large for gestational age with a target threshold of 7.8 mmol/litre.)  2 hour value – less than 6.4 mmol/litre (Rowan et al. [2010] reported a lower incidence of pre-eclampsia and large for gestational age with a target threshold of 6.4 mmol/litre.)


A recent study published 15 September 2017 in the Lancet shows continual glucose monitoring is associated with improved neonatal outcomes in type 1 diabetic patients:

Use of CGM during pregnancy in patients with type 1 diabetes is associated with improved neonatal outcomes, which are likely to be attributed to reduced exposure to maternal hyperglycaemia. CGM should be offered to all pregnant women with type 1 diabetes using intensive insulin therapy. This study is the first to indicate potential for improvements in non-glycaemic health outcomes from CGM use.

Continuous glucose monitoring in pregnant women with type 1 diabetes (CONCEPTT): a multicentre international randomised controlled trial


For more information on testing blood sugar levels and research publication links, check out our testing blood sugar levels page.

It’s your pregnancy, it’s your baby – make an informed decision over test times and targets, but be wary of spikes!

you decide