Work with your health-care provider to develop a plan to reduce your insulin or oral medicine when physical activity is anticipated. There is no way to tell exactly how much the activity will lower your blood glucose, so you might start out by reducing your dose by 33% when activity is planned within 90 minutes of the meal. For more intense activity, a 50% (or greater) reduction can be made; for less intense activity, a 20% or 25% reduction may be sufficient.
For activity that will take place before or between meals, it makes more sense to check your blood glucose and have a snack before you exercise. Again, the size of the snack depends on many variables, including your body size, the nature of the activity, and the timing and amount of your last dose of insulin or oral medicine. As a general rule, people who weigh 100 pounds will need approximately 15–25 grams of carbohydrate per hour of activity to keep their blood glucose steady. Those who weigh 150 pounds will need 20–30 grams; 200 pounds: 25–35 grams; 250 pounds: 30–40 grams, and so on.
Don’t forget that physical activity that is very intense and prolonged can produce a blood glucose drop several hours later. This is called “delayed-onset hypoglycemia.” Many people find that their blood glucose drops during the night following heavy daytime exercise, or in the morning following heavy exercise the night before.
Check your blood glucose more often than usual for up to 24 hours following heavy exercise. If you detect a pattern of delayed-onset hypoglycemia, you can prevent it by consuming extra carbohydrate or by lowering your insulin or oral medicine at the appropriate time. For example, to prevent the late-morning drops following nighttime exercise, try lowering your insulin dose at breakfast by 33%.
8. Be aware of alcohol’s effects.
While many alcoholic drinks contain carbohydrate that raises blood glucose levels fairly quickly, the alcohol itself has a tendency to make blood glucose drop several hours later. This is because alcohol inhibits the liver’s secretion of glucose into the bloodstream. When the liver is releasing less glucose than usual, the blood glucose level may drop.
After drinking alcohol, it is recommended that you reduce your insulin or diabetes medicine dose or consume extra carbohydrate. People who use insulin pumps can lower their basal insulin by 40% to 50% for approximately two hours for every drink consumed. Those who take NPH or Lente at night can lower their dose by a similar percentage after drinking. If you choose to eat to offset alcohol’s blood-glucose-lowering effects, choose a food that will take time to affect blood glucose levels such as ice cream, peanut butter, or yogurt. Fifteen to thirty grams of carbohydrate at bedtime should serve as a good starting point.
9. Check often.
Managing blood glucose is a lot like driving a car. If you pay attention and keep your hands on the wheel, you’re not likely to veer off the road. Close your eyes or let go of the wheel for too long and you’ll probably wind up in a ditch. Likewise, the more often you check your blood glucose, the less likely you are to suffer from extreme highs and lows. Checking before breakfast, lunch, dinner, and bedtime on a consistent basis, whether or not you take insulin or medicine at those times, will allow you to catch potential problems before they become too serious. A blood glucose level of 75 mg/dl at lunchtime should alert you to the need to either reduce your insulin or medicine or have some extra carbohydrate. Without knowing this, you could easily wind up hypoglycemic in the afternoon.
10. If it’s broke, fix it.
Take a good look at your blood glucose monitoring logbook every couple of weeks. If you see too many lows at a particular time of day, do something about it! Don’t keep doing the same things over and over, expecting different results. Perhaps you need to reduce or change your medicine. Maybe your insulin-to-carbohydrate ratio at a particular meal needs to be adjusted. Or maybe you just need to eat more carbohydrate when you are active.
