Ordering Your Exercise to Avoid Hypoglycemia?

This article was originally posted on Jan. 30, 2013.

People with type 1 diabetes have to be cautious when they exercise or do any kind of physical activity to avoid setting their blood glucose levels out of sorts. While exercise is a major factor in managing diabetes, people with type 1 diabetes are at risk for hypoglycemia during and after exercise.

In a recent study, Dr. Jane Yardley, as part of her PhD studies at the University of Ottawa, looked at how the order of resistant and aerobic exercises might affect blood glucose control in people with type 1 diabetes. The findings suggest that type 1 diabetes patients may be able to prevent the risk of hypoglycemia by strength training before doing aerobic exercises.

The study involved 12 physically active men and women (average age 32) with type 1 diabetes. Each participant completed two exercise sessions conducted at least five days apart. In one session, each individual ran on a treadmill for 45 minutes and then lifted weights for 45 minutes. In the other session, the exercise sequence was reversed.

Yardley found that patients who did aerobic exercise first had larger drops in blood glucose evels during their exercise, compared to patients who lifted weights first. Although the order of exercise did not increase the risk of hypoglycemia, the length and severity of hypoglycemia was slightly greater when aerobic exercise was done before weightlifting.

These findings suggest that the order of exercise has a significant effect on controlling blood glucose with exercise.

Yardley explained that, “Strength training increases blood glucose by encouraging the liver to release glucose into the blood stream which stabilizes glucose levels. With aerobic exercise, however, there is an increase in glucose [uptake] from the blood stream and since there isn’t enough glucose being produced there the blood glucose levels drop.”

She suggests that people with type 1 diabetes who tend to have to interrupt their exercise all the time to take in more glucose because they’re dropping low should consider doing resistance/strength training first.

Yardley and her colleagues also recently studied the effects of aerobic exercise and resistance exercise on blood sugar levels in people with type 1 diabetes.

The study examined how aerobic and resistance exercise affected blood glucose levels before and after workouts. Yardley found that blood glucose levels dropped more during aerobic exercise than during resistance exercise. However, after resistance exercises, type 1 diabetes patients had better blood glucose levels than after aerobic exercises.

“When resistance exercise happens first, growth hormone is higher during the entire exercise session which encourages fat to be burned as a fuel rather than glucose,” she said. “Also, at the end of resistance exercises, patients will most likely have a buildup of lactate in their system which can be recycled and turned back into glucose to be used in the form of energy. This can then prevent low blood glucose levels for hours after the physical activity.”

Yardley and colleagues concluded from these findings that resistance exercise causes fewer initial drops in blood sugar during exercise, but is linked with more prolonged decreases in post-exercise blood sugar levels compared to aerobic exercise.

One point Yardley really wanted to stress is that both studies had very small sample sizes with fit individuals who knew how to adjust their insulin and carbohydrate intake levels for the physical activities that they were doing.

“Anyone with type 1 diabetes who is going to undertake an exercise program should always be very careful and check their glucose frequently, as well as check in with their endocrinologist and their diabetes educator,” she explained. “It is important that people with type 1 diabetes look at the patterns of their blood glucose levels before, during, and after exercise because the combination of factors that affect glucose is very complex with a lot of variability.”

If you experience low blood glucose during and after exercise, you can meet with a clinical exercise physiologist who is also a Certified Diabetes Educator at the Joslin Diabetes Center.


  1. Thank you sharing this information. Exercise seems to play a very important role when it comes to managing diabetes. I read how Jay Cutler had to make a number of alterations in his pre-game and during game plan in order to properly manage his blood glucose levels. In an interview he says that while he still needs to check his blood sugar levels multiple times a game, he is getting a better sense of how they react while he is playing.

  2. I became a Heart Lung transplant for cystic fibrosis when I was 33. The medication required, prednisone, sped up the onset of type 1 diabetes (CFs have weak pancreases to start with). I have found that the only way I can keep my A1C below 7 is by weight training 3 times a week. In periods when I haven’t exercised for a few months, my A1C will creep up because the long term effects of the exercise have worn off. I am 57. Weight lifting helping keep your sugars down is a no-brainer to me.

  3. I have had Type I diabetes for almost 50 years and I have exercised for more than 60 years. Hypoglycemia is simply one factor in my exercise routines, but it is definitely not a showstopper. I don’t quite understand the pervasive fear of hypoglycemia when it is so easy to recognize and manage. When I am on a long bike ride or exercising with heavyweights, I simply make sure to have plenty of glucose tabs available. I understand that some diabetics fail to recognize hypoglycemia, but I believe that is simply a matter of paying attention and learning your specific symptoms. In the last five decades I have had thousands upon thousands of hypoglycemic reactions, but I am still moving forward. 97% of all diabetic deaths is due to complications not hypoglycemia. If you have to choose the way to go I will always choose hypoglycemia and lots of exercise.

    To date I have no complications associated with diabetes and yet I was diagnosed with brittle diabetes in the 1960s and I have always had the Dawn phenomena.

    Diabetes is a self managed disease, it cannot be managed by your doctor or your nurse , it is up to you to take the bull by the horns. Managing diabetes is a learning process, if you stop learning you will have to face the piper sooner than later. -Larry

    • Larry, I fully agree with your self-management approach.
      In my 49 years as a T1, I was always lectured by doctors as to dangers of hypoglycemia but never a word about hyperglycemia.
      As you say, one learns how to recover from hypos with glucose tablets & more recently with liquid or gel glucose.
      Since T1s don’t produce insulin or amylin our livers don’t respond quickly to low or high BGs.
      Doctors freak out when I tell them about my daily workout routine — 20 minutes of high intensity interval biking, 20 minutes of weight training & 20 minutes of stretching.
      And I do this while having Cerebral Palsy from birth with left-sided hemiparesis causing muscle spasticity.
      My A1c is consistently between 5.5 & 6.0 & I have no complications apart from dawn phenomenon.

  4. I also am in my 49th year as a Type 1 & have been working out at the gym 5 days a week for an hour for the past 17 years.
    I now check my BG level 30 minutes before starting my workout & immediately after. I try to be at least 5.0 or 90 before I start. This usually prevents a hypo during my workout.
    But if I start with BG over 6.5 or 115, it can result in a high BG level or hyperglycemia after my workout.
    So one has to be aware of both hypos & hypers & what causes them during exercise or workouts.

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