Exercise and Blood Sugar

Does anyone know how long after exercise your blood sugar can be affected?  I have been trying to be more active lately and have been waking up with a lot of lows after exercising that day.  Anyone have any ideas???

24-48-72 hours depending the type, frequency, and duration of your exercise.

cardio exercises (like running, walking, swimming, etc) will affect your blood sugars for a shorter amount of time but with a greater impact (you might notice lower lows)

weight bearing exercises (like weight lifting) will affect your blood sugars for longer but with less impact (you might notice improved sugars, but maybe not lows or the lows won't be as severe).

for the best health benefit (both blood sugar wise and otherwise) a combination of the 2 is best. you may need to start decreasing your insulin doses as you exercise (especially lantus) and/or consume some snacks before and after exercising.

good luck and have fun :o)

Thanks for the info C!  I have mostly been doing cardio....not really ready to do the weight training yet.....I am not really low right after exercise, but I get lower as the night goes on.  It has been weird.  I am going to look at decreasing my lantus at night too.  Thanks again!

Hello Angela,

While don't have an answer to your question I still wanted to respond and say that I hope you find that Happy Medium you are looking for and need.



Exercise can affect your blood sugar for up to 24 hours after exercise. I quite often will exercise through the day and then be affected around 2am and also early on in the next day.

You need to lower your insulin dose if exercise is new to your regime. Would be a good idea if you talk to your health support re this.

Yes I would definitely discuss the matter with your health care professional,  especially if you are considering changing your insulin doses.  I'm not sure how different it is for adults but; my son's doses (basal rates, he's on a pump) do not get changed unless his doctor tells me to change them.  Although; we will sometimes decrease the percentage of his scheduled basal rates prior to bedtime, or at any other time he is a little lower than usual and may be at risk of crashing.  But; that is because his doctor has given us leeway to do so within an agreed upon percentage range at out discretion.   


C, I haven't heard that before, that cardio and weight-bearing exercise will affect blood sugar for different lengths of time. Do you know where I can read more about that?


haha, well if you want to read my advanced human nutrition and metabolism book, that's where i got it :o) the reason they affect blood sugars differently is because they have differing affects on metabolism. weight bearing exercises and exercises that build muscle increase the metabolism for longer periods of time (meaning you burn more calories while resting for longer periods of time), where as cardio exercises will boost the metabolism temporarily (meaning you only burn more calories at rest for a short period of time).