Which Type of Exercise Is Best for Managing Diabetes, Aerobic Exercise or Weightlifting?
By Tom Lang
What are the different types of exercise and how do they affect your glucose levels?
Exercising is one of the best ways to manage your diabetes. But which type of exercise – aerobic or anaerobic (which includes weightlifting and resistance training) – is most effective at managing your blood glucose?
The most important exercise factor is…
Regardless of what kind of exercise you do, the most important thing is to do some form of exercise daily and to have fun doing it!
When you exercise regularly, you will find that managing your diabetes is easier, and you may reduce the risks of long-term complications like heart disease, nerve damage (neuropathy) and other serious conditions.
How does exercise affect insulin and blood glucose?
Exercise is beneficial for people with diabetes because it can lower your glucose levels not only during, but for up to 24 hours after a workout. The American Diabetes Association (ADA) explains, “As you exercise more, your body becomes better at processing glucose and your insulin sensitivity increases.”
Aerobic exercises (like walking, running, swimming, or cycling) may cause your glucose levels to fall as your body uses the glucose for energy.
On the other hand, short duration and anaerobic exercise (like quick sprints or weightlifting) may raise your blood glucose because they trigger hormones, such as adrenaline, that release stored glucose from your liver and cause your body to make glucose from fat.
However, your own results may vary based on how much muscle you have, your nutrition, your current level of fitness, and the duration and intensity of your physical activity, among other factors.
Aerobic exercises include activities like walking (at a medium to fast pace on level ground, or a slower pace on steep hills), running, swimming, tennis, biking, hiking, jump rope, skiing, ice skating, dancercise, and any other sport or activity that gets your heart rate beating faster.
As a general guide, the ADA recommends doing 30 minutes of aerobic exercise on most days of the week. Start with a short exercise session if you haven’t been exercising regularly and add a few minutes each day until you can continually exercise for 30 minutes. Once you hit 30 minutes, slowly start to increase your time, or stay at 30 minutes and increase the intensity level of the exercise, or for maximum benefit, do both. Whichever works best for you.
You can make small changes in your daily habits that can give you big benefits, like taking the stairs instead of the elevator whenever possible, walking or biking to the grocery store instead of driving, taking two minute breaks every half hour, or hour, to do squats, push-ups, walking the stairs, etc., to get your heart rate up. Every bit counts!
If you are lucky enough to have a gym at home or at work, get some exercise in before work, before your lunch break and/or before you go home. Two or three 10 minute exercise sessions may be just as beneficial as one longer session, and they may be easier to fit into your schedule.
Anaerobic exercise (strength and resistance training)
Strength training includes using weights, doing calisthenics, using weight machines, resistance bands, medicine balls and your own body weight to create resistance during exercises like squats, planks, push-ups, pull ups, chin ups – which are easy to do at work or when traveling – and all these exercises are designed to improve your strength and endurance.
You can easily combine aerobic and strength training by simply holding dumbbell weights, or other weights, while you do squats or an exercise known as “Farmer’s Walks.”
Burning fat and adding more muscle is a great way to better manage your blood glucose because muscles use more glucose than fat, even when you are not exercising.
Some things to consider before you start a strength training regimen:
Always consult with your healthcare provider before you start a new fitness program.
A beginner needs to train two or three times per week to gain the maximum benefits.
Rest each muscle group for at least 24-48 hours to maximize gains in muscle strength and size.
Varying your workouts can help you push past a training plateau.
If you’re not familiar with weightlifting, seek out a trainer to show you how to exercise properly. This can help you avoid injury and maximize your benefits. Your initial goal should be about 20-30 minutes of strength training, two to three days a week.
Why do aerobic exercise and anaerobic exercise affect your glucose levels differently?
Oxygen isn’t the only difference between aerobic and anaerobic exercise. Your body also powers them differently. When you’re working aerobically (like walking or running), fat and glucose provide energy.
Move anaerobically – as you would during a sprint – and the body pulls glycogen (stored glucose) from the muscles to be used for fuel. The depleted glycogen stores and buildup of lactic acid during high-intensity anaerobic exercise are part of why the activity can make your muscles so tired.
Like aerobic exercise, anaerobic exercise burns calories and improves your cardiovascular health, insulin sensitivity and blood glucose management. There’s a big difference for your muscles, though: anaerobic exercise also improves power and builds muscle strength and mass.
How to address hypoglycemia during exercise
Hypoglycemia occurs when your glucose levels fall below 70 mg/dL. This could happen if you exercise so intensely that your heart rate remains elevated for a long time. Especially if you have type 1 diabetes or use insulin to manage type 2 diabetes, always check your glucose before and after you exercise to prevent hypoglycemia.
Be prepared in case your blood glucose starts to drop quickly, or is getting too low and wait to resume exercising until your blood sugars stabilize.
15-20 grams of fast-acting carbs to quickly raise your blood sugars can be:
4 glucose tablets (4 grams per tablet), or
1 glucose gel tube (15 grams per gel tube), or
4 ounces (1/2 cup or 118 ml) of juice or regular soda (not diet soda), or
1 tablespoon (15 ml) of sugar or honey, or
5 lifesaver candies
To read about more options, check out this 15 Gram Carbohydrate Food List.
Check your glucose levels again after 15 minutes. If it's still too low, have another 15 grams of carbs and wait. Repeat this every 15 minutes.
There is some evidence that men are at a greater risk than women for hypoglycemia during or after weightlifting or resistance exercise, but by checking your glucose before, during, and after exercising, you can prevent hypoglycemia.
The time of day you exercise may also affect your insulin needs
For example, in the morning, glucose levels tend to decrease less with exercise because hormones produced in the morning help raise glucose levels. On the other hand, in the afternoon, levels of the same hormone fall, so you may need to temporarily reduce your insulin dose to prevent hypoglycemia.
It’s important to always consult with your healthcare provider before you make any adjustments to your medications to find what works best for you and your level of physical activity.
Remember, to better manage your diabetes, with the fabulous side benefits of looking and feeling better, you need to “Just do it!” Make exercise something you truly love doing:
Talk with your doctor or healthcare provider before you make any major changes to your exercise or activity routine.
Always check your glucose levels before and after exercising
Start small, with a short exercise session and add just one more minute each time. Making small, healthy changes in your daily activity will lead to bigger improvements in your overall health and dramatically increase the likelihood that your new habits will stick with you for the rest of your life.
Make it fun and enjoyable by exercising to your favorite music, sounds of nature, while watching TV or a movie, or while listening to a motivational talk. Exercise with a partner or buddy, if possible
Combine your favorite aerobic exercises with strength training and healthy eating habits for the best results.
Be prepared for hypoglycemia. Always have some juice or glucose tablets and a healthy snack with you when you exercise. Stop exercising if you feel lightheaded or have symptoms of hypoglycemia.
Managing your diabetes takes time, so don’t expect magical results in just a week or two. Stick with it and you will be pleased! To develop a personal exercise plan that best suits you, talk with your healthcare team.