This is essential, as it will give you an indication of what direction your blood sugars are heading.
If your blood sugar is below 100 prior to exercising...
Eat a snack that provides 15 grams of carbohydrates.
See the meal plans at TheBestLife.com/diabetes for ideas.
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.