- Sheri Colberg, PhD
What You Need to Know about Diabetes and Exercise
Here are important things everyone needs to know about exercise and diabetes:
Many times, exercise can virtually erase your blood glucose mistakes. It acts as an extra dose of insulin by getting the glucose out of your blood and into your muscles without insulin (through an insulin-independent mechanism related to muscle contractions themselves). When you’re not active, your body needs insulin to stimulate that uptake. Being regularly active makes your muscles more sensitive to any insulin in your body as well, so it takes less to get the job done. What better way to help erase a little overeating of carbs (or a slight lack of insulin or insulin resistance) than a moderate dose of exercise?
Exercise doesn’t always make your blood glucose come down, at least not right away. When you do intense exercise, glucose-raising hormones (like adrenaline and glucagon) can actually raise your blood glucose instead, albeit usually only temporarily. This phenomenon is true for people with any type of diabetes and even for anyone without diabetes. However, even if a workout raises it in the short run, over a longer period of time (2-3 hours), the residual effects of the exercise will bring your blood glucose back down while you’re replacing the carbs in your muscles. If you take insulin, be careful to take less than normal to correct a post-workout high or your blood glucose will likely be crashing low a few hours later. If you don’t take insulin, give it some time to come back down or do a cool-down with less intense exercise (like less-than-brisk walking) to help bring it back to normal.
How much muscle you have really makes a big difference to your blood glucose control (see prior blog on this topic). Exercise helps you build and retain your muscle mass, which is the main place you store carbs after you eat them. Almost any type of exercise uses up some of your muscle glycogen stores, but if you don’t exercise regularly, your muscles remain packed with it. There is a maximal amount that fits in muscles, which is why building up your muscle mass helps with being able to handle the carbs you eat more effectively. Your liver stores some glucose as glycogen, but not that much relative to your muscles’ total storage capacity. Being sedentary ensures that no amount of insulin is going to be able stimulate more blood glucose uptake into your muscles. Without regular exercise to use up some of that glycogen, you really have nowhere to store carbs, so your blood glucose goes up and some of the excess gets turned into body fat instead. Doing resistance or heavier aerobic training is critical to maintaining the muscle mass you have and offsetting the effects of getting older as much as possible.
People with naturally lower levels of insulin generally live longer (think of centenarians and elite athletes, both of whom have low insulin levels). Exercise helps you keep your insulin needs low, which makes it easier to either make enough of your own or get by with much smaller doses (resulting in less of a margin for big errors in dosing). Plus, It’s really a lot harder to lose body fat if your insulin levels are high or you take large doses because insulin promotes fat storage from excess blood glucose. Both the last time you exercised and how regularly you're active have an impact on the insulin sensitivity of your muscles, so aim to exercise as least every other day (although daily is likely better) and keep all those muscle fibers you have by using them regularly.
Diabetes aside, exercise is about the best medicine that there is for so many other health conditions. Being active is one of the best ways to control emotional stress and to stave off depression—far better than antidepressant medications and with no bad side-effects! What’s more, exercise naturally bestows your body with antioxidant effect, which is why regular exercisers are less likely to develop most types of cancer. They also generally feel and act younger than their chronological age and are less likely to even get a cold if doing moderate amounts of regular exercise.
Finally, there are many different ways to exercise, including standing up more, taking extra steps during the day, fidgeting, and just generally being on the move whenever and wherever possible. Knowing that hopefully takes away all of your excuses for not being more active. If you can’t get in a “planned” workout on any given day, you can certainly add in more steps or other activity all day long instead (or do it in addition to your usual exercise). Every bit of movement you do during the day counts, so fidget away as part of your daily dose of exercise!