Dietitian Susan Weiner—a consultant in the writing of The Best Life Guide to Managing Diabetes and Pre-Diabetes by Bob Greene—offers her expertise on how to exercise when you have diabetes.
I exercise three times per week. Should I alter my meal plan on the days I exercise?
Yes, your meal plans may need to be adjusted on the days you work out. That's because exercise affects the way your body regulates insulin and other hormones, which in turn will affect how many carbs and how much medication you need to keep your blood sugar in a healthy zone. A nice bonus: Over the long run, physical activity improves insulin sensitivity, meaning you need less insulin to drive sugar into the body's cells, which can have the happy side effect of lowering your medication doses.
On some medications, exercise can cause blood sugar to drop. During exercise, your muscles require a lot of glucose to fuel your workout. To help get more glucose into the muscles, muscle cells temporarily become more insulin sensitive. So if you take insulin or a drug that stimulates your own insulin production, your regular dose may be too high, driving too much blood sugar into the muscles and leaving too little in the bloodstream. The result: Blood sugar drops, maybe a little, maybe to hypoglycemic levels. Chances are you'll need a lower dose before exercising—but don't make any adjustments without checking with your doctor.
Another reason blood sugar could drop during exercise is because you're not producing enough adrenaline, which is a problem for people with autonomic neuropathy—a common complication of diabetes.
You may know that adrenaline, the fight-or-flight hormone, increases heart rate and breathing and improves oxygen delivery to your muscles. But it also stimulates the release of glucose from glycogen, the stored form of glucose in muscle and liver. Unfortunately, when you have autonomic neuropathy—damage to the nerves that control many of the body's involuntary functions—adrenaline release may be reduced, which means that not enough blood sugar will be released and you'll wind up with low blood sugar.
And in some cases, exercise can cause your blood sugar to spike. If you don't have a problem releasing adrenaline, then it does its job, sending extra glucose into the bloodstream. But if you don't have enough insulin to "cover" all this extra glucose, your blood sugar could become too high, sometimes staying high for a period of time following the workout.
This might make you a little nervous or frightened—but don't be. Simply know that when you start exercising more, you may need to work with your doctor to adjust your medication as well as your pre-exercise carbohydrate levels (as explained below). And you should test your blood sugar before, during and after exercise, as your reactions to exercise aren't always predictable.
The Best Life plan for diabetes can help make sure you get the right combination of carbohydrates and calories, working along with your prescribed medications, to keep your blood sugar levels regulated as you increase your physical activity.
Ideally, have one of your snacks from your meal plan, so you're not adding extra calories. Retest your blood sugar in about 15 minutes, and if it goes above 100, you can start your workout. If not, continue the cycle of testing until your blood sugar levels rise. If your blood sugar doesn't move above 100 after three tries, then do not exercise. Just skip exercise that day—you are at risk for a hypoglycemic reaction.
If your blood sugar is in a safe range—between 100 and 200, or a target set by your physician... Go ahead and exercise. In the 200 to 250 range, it is safe to start exercising, but be cautious! Check your blood sugar about 15 minutes into your exercise routine. If you are exercising for more then one hour, check your blood sugar every 30 minutes. If it rises above 250, stop exercising until it levels off, and test again in about 15 minutes.
If your blood sugar is over 250... This is an indication that something might be wrong, and you should probably not exercise on that day. Perhaps you ate too much carbohydrate, you forgot to take your medication, or you're sick.
You might notice that you're urinating more often with a high blood sugar. This could lead to dehydration, which is yet another reason not to exercise until your blood sugar comes back into an acceptable range.
However, if your blood sugar falls below 250 and stays that way for several hours and you've pinpointed why it was elevated in the first place, then feel free to exercise. It is very important to test your blood sugar regularly that day—even for several hours after exercising—to make sure that your blood sugars do not spike or fall out of the acceptable range. Test Again If you are on insulin or are taking an oral medication that increases insulin, you must continue to check your blood sugar about every 15 minutes during the workout to make sure that your blood sugar doesn't dip below 100. If you're not taking one of these medications, it's okay to wait until after your workout to test again.
If it does drop below 100, stop exercising and eat an additional 15 grams of carbohydrates, again using one of your snacks on the meal plan. If you've used up all your snacks for the day, go ahead and have another one—safety first!
If you do not feel well while exercising, stop right away and test your blood sugar. Remember, the only way to know if your blood sugar is high or low is to test.
If your blood sugars continue to stay in the normal range, focus on moving to the next level of exercise. For those of you who don't experience extremes in blood sugar—hypoglycemia or hyperglycemia—while exercising, increasing the duration (how long you're exercising) or intensity (how hard you're exercising) will prove to be a terrific accomplishment.
The Best Life diabetes plan encourages you to strive to be more physically active while keeping your blood sugar level in your target range.
Check In with Your Doctor It's always a good idea to speak with your doctor before changing your nutrition or exercise program if you have pre-diabetes or diabetes. As you increase your activity and/or reduce your intake of carbs and calories, your doctor might decide you need less insulin or oral medication.