Low Blood Sugar After Workout - Please Help


I have started going to Gym to try and improve my fitness and control my diabetes better. I was advised by my Diabetic Nurse that the working out will help control my diabetes and also my blood pressure. I take Humalin M3 twice a day 40 units in the morning and 40 units at night. I checked my blood sugar level before going to the Gym and it was 12.9. after the gym I checked again and it was 3.8. I had two small oranges straight after my blood sugar level readings. When I went home I then had a bowl of Museli ( 18 grams of carbs) with milk and a slice of wholemeal bread (14 grams of carbs) I then waited 5 hours before I had took my Insulin. Because I was advised by my Diabetic Nurse to reduce my insulin after excerise I took 35 units. I then had Dinner which was Chicken Breast with wholegrain rice (because it was Uncle Ben one serving contained 31.2grams of carbs… I then checked my blood sugar level at 9:30 which was 2 1/2 hours after meal and it was 1.9. I am shocked it went so low because of all the carbs I had after the Gym. I then had 2 slices of wholemeal bread, banana, 4 sweets (skittles). I then waited 1 hour and checked again it was up to 4.9. I then woke up about 2am and my blood sugar level was 1.8 I really do not understand why my blood sugar was dropping so quickly even after the carbs after the Gym.From my carb count after the Gym and dinner my meal I make it over 60 grams of carbs so I do not understand why my blood sugar was 1.9 at 9.30. If anyone can help to understand I would be great up.



Sounds like you’re having a pretty tough time with that

Exercise will have the immediate effect of increasing your insulin sensitivity. A basal of 40 units morning and evening is already pretty high and you could find needs adjusting (reducing) by more than 5 units on a day that you exercise. (Exercise regularly and you will need even less)
It’s hard to offer much advice without understanding a bit more about your activity - so how long did you exercise for? How hard did you work out (what was the level of intensity) etc. All of this impacts on what you would ordinarily expect with your activity.
I was a bit confused by your comment ‘I waited 5 hours before I took my insulin’ - do you mean you waited 5 hrs before you bolused for the meal, or was that when you had your ‘morning’ basal? (Apologies for being a bit dense!)

To help you out a bit, for an hour of aerobic exercise you can pretty much expect to burn through 60g carbohydrate. In order not to suffer with low blood sugars later on in the day or that night, (and assuming your body is not adapted to running super low carb) then you’re going to have to expect to at least replace that amount of energy.

When you exercise, your muscles and liver become depleted of glucose. They have to replace this by drawing glucose out of the blood stream. If you burnt more than 60g of carbs during your exercise, then there is every chance you will suffer a low blood glucose level at some point after your activity. The opportunity for this can be exacerbated by taking a large dose of insulin, as it enables the muscles to take up glucose much more readily (so you can see a rapid blood glucose fall).

Have you considered getting a insulin pump?

Unfortunately there is no magic answer for you - it’s just going to take a bit of trial and error, lots of testing and note taking. Before long you’ll start to see a pattern and be able to work out a strategy that works though, so keep it up!