Living with type 1 diabetes requires you to regularly check your blood sugar levels before you eat. However, we may not always consider what happens to our sugar levels immediately after we eat; despite it being very normal for people who don’t have diabetes, let alone those who do, to temporarily have high sugar levels.
Given that having high sugar levels can give you symptoms like thirst, tiredness and needing to go to the toilet a lot, learning about ways to try and reduce spikes in your sugar levels after meals may make a difference to your overall health and wellbeing.
Why do people get blood sugar spikes after meals?
When people eat a meal, especially when it contains carbohydrates, it is normal for them to have a temporary spike in their sugar level (often known as a post-prandial spike) before the insulin their body produces immediately starts working to lower the spike. For someone with type 1 diabetes, who can’t produce their own insulin, these spikes can be higher and last longer
This is because it can take longer for the type of insulin they inject (or that is delivered via an insulin pump) to start working, in comparison to the insulin that is produced naturally by the body of someone who does not have diabetes, to reduce these post-meal spikes.
Furthermore, it is important to know that people living with type 1 diabetes may have alterations in different digestive enzymes which will cause faster digestion of our meals (resulting in the glucose reaching the bloodstream faster). This can obviously impact on the size of the spike too.
Why is it important to reduce the size and duration of these spikes?
Reducing these spikes may help you to increase the amount of time you spend in your target blood sugar range (also known as the time in range), which will have a positive impact on your future health. You should consult your healthcare team to understand the best target range for you, as this will differ from person to person. However, the International Society for Paediatric and Adolescent Diabetes (ISPAD) recommends a target of 5.0-10.0 mmol/L (after meals, when there is no longer any active bolus insulin on board).
Symptoms of a high blood sugar level also vary in individuals, but they may cause you to feel thirsty, tired, stressed and need to go to the toilet a lot. In the short term, by avoiding prolonged high blood sugar readings after eating, you should also reduce the occurrence of these symptoms and improve your energy, cognitive (thinking) and athletic ability and overall mood.
How do I detect spikes in my sugar levels?
The exact timing of blood sugar spikes can vary from person to person and meal to meal. However, on average, the post-meal peaks tend to be about one hour and 15 minutes after starting a meal.
The best way to measure post-meal patterns is by using a continuous glucose monitor (CGM) or Flash monitors. These devices can give you a clear view, including graphs, of what happens with the glucose levels after meals without the need for finger pricking (image below). You can ask your diabetes health team if they are available for you as they are not available to everybody.
If you are not using a CGM, then please speak to your healthcare team about the best way to do this for you with finger prick testing.
How do I know it is a spike?
There is no universal answer or specific guidelines on when a sugar level is too high after meals. However, if post-meal readings are consistently above your target range (or the recommendations from ISPAD 5mmol/L to 10mmol/L), then you should discuss whether it would be beneficial for you to address these spikes and how to do this, with your healthcare team (see below for some suggestions for your discussion).
If you are reviewing your post-breakfast sugar levels, you should also be aware of changes in your hormones in the morning, which cause increases in sugar levels (this is known as the dawn phenomenon). This Digibete video may help.
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