I am a 37 year old female with type 1 diabetes and hypothyroidism. I am currently taking Lantus at night along with appropriate amounts of Humalog at meals, and my blood sugars are in good control (70 to 110 mg/dl [3.8-6.1 mmol/L]). I am trying to lose weight and thus would like to decrease my insulin intake. I exercise daily doing either step aerobics or Body Pump (a form of weight training) for 45 and 60 minutes respectively, and my blood sugar rises 40-50 mg/dl [2.2-2.8 mmol/L]. For instance, this morning, before exercise my blood sugar was 100 mg/dl [5.6 mmol/L], and after exercising, it had risen to 146 mg/dl [8.1 mmol/L]. Why is this?

Although most people find their blood sugar drops after exercise, a small number of people find it rises. One theory is that exercise stimulates stress hormones that raise the blood sugar, but the exact mechanism isn’t clear.

If you don’t want to take extra insulin to prevent the rise in blood sugar, you could eat a little less before exercise. Just make sure you don’t then drop a few hours later (If that happens you could eat a little less before exercise, but then eat some more after the exercise).

TGL
Additional comments from Barb Schreiner, diabetes nurse specialist:

When are you checking your blood sugar following exercise? If it is immediately following exercise, you are probably seeing the effect of your body moving glucose out to the muscle. You see, exercise causes adrenaline to be released. One of this hormone’s jobs is to release glucose from its storage in the liver. If you test too soon after exercise you will see this process. Try checking a blood sugar about 45-60 minutes after exercise. Adrenaline has shut off and glucose is returning to stored tissues.

BS
Additional comments from Dr. Andrea Scaramuzza:

When blood sugar rise after exercise it will mean that the insulinisation in that moment is insufficient. So you can evaluate the possibility to increase the dose of Lantus, otherwise you can divide the total amount of Lantus into two doses (one at morning and the other at dinner), or again if you inject Lantus at dinner you can prove to switch it at morning time. Discuss with your diabetes doctor.

AS
Additional comments from Dr. Stuart Brink:

First of all, this is a pretty small blood glucose rise and not likely
causing much problem short term or long term. If exercise cause a rise in blood glucose level
this could be a simply

adrenalin
stress response and quite normal with or
without diabetes. If the blood glucose levels rose much more, then this would likely
indicate insulin deficiency at the time the muscles required insulin and energy
supplied. Since you do not rise very much and do not report post-exercise
hypoglycemia either, sounds like you are in good balance with your food, insulin and
activities.

SB