How Does Exercise Affect Blood Sugar?
When you exercise, your body needs extra energy from blood sugar, also called glucose.
When you do something quickly, like a sprint to catch the bus, your muscles and liver release glucose for fuel.
Exercise usually lowers your levels. If you take insulin or diabetes meds, a boost in workout intensity or length can mean you’ll have to adjust your snacks, medication, or both. Talk to your doctor about what’s right for you.
The big payoff comes when you do moderate exercise for a longer time, like a hike. Your muscles take up much more glucose when you do that. This helps lower your blood sugar levels. If you're doing intense exercise, your blood sugar levels may rise, temporarily, after you stop.
Exercise that’s too hard can raise your blood sugar by making it harder for your muscle cells to use insulin. A workout helps pump you up by causing small tears in muscle fibers. When they heal, your muscles are stronger. But if you aren’t used to super-tough workouts like HIIT (high-intensity interval training), they can do so much damage that days go by before you feel like moving again. During that time, your muscle cells can’t use insulin well, and that will boost your blood sugar.
It may also rise if you skip workouts. If you’re so sore you can’t make your next gym session, you probably need to dial it down. There’s no rush: It’s better to build intensity slowly as you get used to a new routine. You’re more likely to stick with it if you don’t feel like you’ve been through the wringer.
How Much Exercise Per Week?
Experts say people with diabetes should shoot for:
150 minutes or more of aerobic exercise each week. Studies have shown that regular aerobic exercise can make insulin work better and lower blood sugar long-term. And it makes you less likely to have health problems linked to diabetes, like heart disease.
Two or three sessions of strength training each week. The more muscle mass you have, the better your body can handle blood sugar. Working muscles first use stored sugars and then blood sugars for energy. Muscle also burns more calories than fat. Lifting weights, sit-ups, pushups, and resistance exercises will help.
Will It Hurt Your Joints?
Long-term diabetes can affect them. Over time, blood sugar starts to build up in them, a process called “glycation.” Good control over your disease can help delay it, but the longer you have diabetes, the more likely it will happen.
Glycation can make your joints stiff and brittle. Pounding away with HIIT or making a lot of fast moves might be risky -- one wrong move could lead to an injury. Routines that have you do the same moves over and over can cause problems. Stiff joints can also take a toll on your balance, setting you up for a fall.
Many people with type 2 diabetes take cholesterol medications called statins. They can cause muscle or joint pain, making it tough for you to do high-impact moves correctly or quickly. These drugs also make muscle or joint injuries more likely.
On the other hand, workouts like yoga, Pilates, and tai chi are good choices. They’ll help you build your strength, balance, and flexibility.
Do You Have Any Complications?
Some of the health problems that go along with type 2 can get worse or boost your odds of an injury, depending on what kind of exercise you do.
Diabetes-related nerve damage. The kind your doctor calls "peripheral neuropathy" can make you lose feeling in your feet and toes. It can also affect your balance and raise your chances of falling. If you have it, try not to run or jump. Choose an exercise that doesn’t impact your joints, like swimming.
Another kind of nerve damage, autonomic neuropathy, can make you faint if you move around too fast.
Eye problems. Diabetes can cause new blood vessels to grow in your eyes -- your doctor might call this "proliferative retinopathy." They’re weak and often leaky. When you jump, lift heavy weights, make jarring moves, or hold your head down (as in certain yoga poses), these fragile blood vessels could bleed. If you’ve had a dilated eye exam in the last year, your eye doctor can tell you if the workouts you’re interested in are safe.
If all you want to do is switch from one moderate type of exercise to another, you probably don’t need to discuss it with your doctor. But if you want to ramp up your workout from moderate to intense, get checked out first. You might not be aware you’ve lost feeling in your feet, and diabetes-related eye disease often has no symptoms early on.
Exercise Tips for Type 2 Diabetes
Exercise is sure to be on your to-do list if you have diabetes. Get started with these go-to tips:
1. Make a list of fun activities. You have lots of options, and you don't have to go to a gym. What sounds good? Think about something you've always wanted to try or something you enjoyed in the past. Sports, dancing, yoga, walking, and swimming are a few ideas. Anything that raises your heart rate counts.
Adventure sports like rock climbing or scuba diving should be safe if you’re in good health aside from diabetes. Make sure to get the right training. Don’t do these activities alone because you may need help if your blood sugar gets too low (what doctors call "hypoglycemia"). Take some fast-acting carbs like a sports gel, glucose tablets, or even a tube of cake icing with you.
2. Get your doctor's OK. Let them know what you want to do. They can make sure you're ready for it. They'll also check to see if you need to change your meals, insulin, or diabetes medicines. Your doctor can also let you know if the time of day you exercise matters.
3. Check your blood sugar. Ask your doctor if you should check it before exercise. If you plan to work out for more than an hour, check your blood sugar levels regularly during your workout so you’ll know if you need a snack. Check your blood sugar after every workout so that you can adjust if needed.
4. Carry carbs. Workouts can lower your blood sugar. Always keep a small carbohydrate snack, like fruit or a fruit drink, on hand in case your blood sugar gets low.
5. Ease into it. If you're not active now, start with 10 minutes of exercise at a time. Gradually work up to 30 minutes a day. Stop exercising if you feel shaky, anxious, weak, or confused, you sweat more than usual, your heart is racing, or you have a headache.
6. Strength train at least twice a week. It can improve blood sugar control. You can lift weights or work with resistance bands. Or you can do moves like pushups, lunges, and squats, which use your own body weight. Your strength training program should work your whole body. Set up your schedule so that you work different muscle groups on different days, or do a longer workout less often. It's a good idea to work with a certified fitness instructor or trainer so you learn the right way to do each exercise.
7. Make it a habit. Exercise, eat, and take your medicines at the same time each day to prevent low blood sugar, also called hypoglycemia.
8. Go public. Work out with someone who knows you have diabetes and knows what to do if your blood sugar gets too low. Text a buddy and ask them to join you. The time really does go faster when you have good company and someone to cheer you on! It's more fun, too. Also wear a medical identification tag, or carry a card that says you have diabetes, just in case.
9. Be good to your feet. Wear athletic shoes that are in good shape and are the right type for your activity. For instance, don't jog in tennis shoes because your foot needs a different type of support when you run. Your sneakers should fit well and have plenty of room in the toe.
Check and clean your feet daily for blisters, cuts, bumps, redness, or sores -- even if you didn't work out that day. Let your doctor know if you notice any new foot problems.
10. Hydrate. Drink water before, during, and after exercise, even if you're not thirsty.
11. Stop if something suddenly hurts. If your muscles are mildly sore, that's normal. Sudden pain isn't. You're not likely to get injured unless you do too much, too soon.
Benefits of Exercise for Type 2 Diabetes
Remember how much exercise does for you, including:
- Helps your body use insulin, which controls your blood sugar
- Burns extra body fat
- Strengthens muscles and bones
- Lowers blood pressure
- Cuts LDL (“bad”) cholesterol
- Raises HDL (“good”) cholesterol
- Improves blood flow
- Makes heart disease and stroke less likely
- Boosts energy and mood
- Tames stress