Glucose variability

Why is it that doing the same activity at the same time after the same breakfast can sometimes be managed perfectly and sometimes can be a nightmare?


Here are a few ideas to help reduce that variability!


  1. Body temperature

It is well known that in warm temperatures when the body is trying to cool down and the blood flows nearer to the skin surface any insulin injected will be absorbed quicker and will seem to work much better. The opposite is also true.


So the same dose of insulin may have a different effect depending on what the weather is like!


  1. Injection site

If the weather can affect the insulin absorption then imagine what happens to the insulin sitting above a muscle which is working really hard exercising! That muscle will get a really good blood supply and will get hot and the insulin will work much better. Try injecting at a site away from the muscles that are going to be used. For example, if you are cycling, try injecting into your stomach rather than thighs.


  1. Time after eating

Injected insulin with a meal is designed to work best after about 2 hours so if your exercise happens at about 2 hours after your food insulin then the risk of your blood sugar dropping is much more than if you exercise 3-4 hours after eating when that insulin is wearing off. If you are exercising 1-2 hours after eating and injecting it may be that you need more carbs to keep your sugar up or a bigger cut in your insulin with that meal before exercising.


  1. Muscle groups used in exercise

The rate your body will use up the sugar in your blood will depend also on the number and size of the muscles being used. It seems a bit odd but actually the more muscle groups you use…the less glucose the body uses up! So, running actually uses less glucose up than cycling.


  1. Exercise regime

Aerobic and anaerobic exercise use different pathways to use energy so combining these two types may be helpful.

If you do anaerobic exercise first (eg. squats, weights) then aerobic, then the blood sugar tends to stay more stable and if anything tends to go up a little after exercising.


If you do aerobic exercise first (eg. running, swimming, dancing) then anaerobic then the blood sugar tends to go down after exercise.


  1. Previous exercise

Doing a bout of exercise in the morning can leave 2 things to think about later in the day!

Firstly, the body may not have had chance to build up its energy stores for later in the day making low blood sugar more likely.


Secondly, the body’s response to low blood sugar isn’t as sharp as it usually is after a bout of exercise so you may not get such  good warning signs.

So, being active in the afternoon after exercise in the morning may make things slightly more difficult to manage.


  1. Previous hypoglycaemia

Having had a period of low blood sugar, the body doesn’t respond to further low blood sugars quite as well and the signs of the blood sugar dropping may disappear. If this is combined with exercise it can make the exercise quite difficult to manage.


It is recommended to avoid exercise for 24 hours after a significant episode of low blood sugar.


  1. The excitement of it all

Different emotions can cause cause all sorts of problems with blood sugar control! Excitement and stress can cause the blood sugar to rise quite dramatically. If your sport or exercise suddenly becomes competitive and extra excitement is added such as an important match or competition then those extra stresses can really change the way the blood sugar behaves.


Often this will cause the blood sugar to go up and extra insulin may be needed to bring it down again.




It’s all about keeping an eye on how your blood sugar is doing and adjusting it next time!