HELP ON DIABETES

RECOMMENDATIONS FOR EXERCISE IN TYPE 1 DIABETES

If you have type 1 diabetes, consider taking the following steps.

Keep an Exercise Log

Write down when you are exercising, the relation to the previous meal and insulin bolus, the type of exercise, the duration and intensity, how much carbohydrate (CHO) was consumed before, during, and after exercise, and blood glucose levels (see Figure 9-2). This information is essential for making appropriate changes the next time you exercise.

Plan Your Exercise

Plan how long you will exercise, how intense it will be, and how soon after a meal you will exercise. Try to be consistent from day to day.

Monitor Blood Glucose Levels

Take your glucose meter with you when you exercise, and check your blood glucose levels before, during (at least once or twice), and after exercise. If possible check them at least two or three times at half-hour intervals before the exercise to find out the direction of glucose changes. Prick your finger for the blood sample—do not use your forearm, because there may be a five- to twenty-minute lag in the glucose response in the arm.

With intense exercise, be prepared for lower glucose levels several hours after exercise, for example, in the middle of the night. Have a bedtime snack, or wake up and check your blood glucose.

Adjust the Insulin Dose

Before exercise, adjust the bolus or basal insulin, or both, in anticipation of the exercise.

• A bolus of a fast-acting insulin analog lasts for about four hours, and the peak is at about one to one and a half hours. If you exercise within two hours, you will need to cut back on the premeal bolus (to 50 to 75 percent of your usual dose). 
• Making an adjustment in basal insulin dosing is easier if you are on an insulin pump. If you are planning for exercise of long duration (longer than ninety minutes), you may want to cut back the amount of your basal insulin for up to two hours before the exercise. If you are participating in competitive sports, you may find that the “adrenaline rush” means that you may have to increase your basal insulin temporarily for up to two hours before the exercise. 
• Adjusting the basal dosage of the long-acting insulins like glargine or detemir is trickier—you can try cutting back to 50 to 80 percent of the dose on the days you exercise. Any high glucose levels earlier in the day can be covered by giving additional bolus insulin. 

During exercise your options will depend whether you are on a pump or on injections.

• If you are on the pump, you have a number of options as to what to do regarding the basal insulin delivery. For short-duration exercise lasting an hour or so, you can simply come off the pump. If the pump is taken off for more than an hour (for example, while swimming), a small bolus may be given before coming off. If you will be exercising for several hours, a temporary basal amount (20 to 75 percent of your usual dose) might be necessary. For example, if you go cross-country skiing for several hours, you may change your basal to 20 to 50 percent of your usual dose for the duration of the exercise. A similar change may be required for a marathon. 
• If you are on insulin glargine or detemir, you do not have the option of changing the basal rate during exercise: your only option is to consume additional carbohydrates. 

  After exercise you will adjust the bolus and basal insulins for the acute effects of exercise and also for the effects of chronic exercise.

• If you get predictably high glucose levels after exercise, be prepared to give a little bolus of a fast-acting insulin analog. With intense and/ or prolonged exercise, hypoglycemia can occur several hours (up to twelve to sixteen hours) afterward, and you should be prepared to reduce the basal insulin (or eat a snack). You might consider purchasing a continuous glucose monitoring system that can alert you to overnight hypoglycemia. 
• After a weekend of increased physical activity such as skiing, a reduction in insulin requirements may persist for an additional twenty-four hours. 
• With exercise training, you may become more insulin sensitive, and you may need to change your usual insulin regimen by cutting back on both basal and bolus insulin doses. 

Eat Carbohydrates

For athletes with diabetes, it is recommended that 55 to 60 percent of the total daily kilocalories should be carbohydrates. Endurance athletes (such as long-distance runners or cyclists) should consider eating a carbohydrate-rich meal (1 to 2 grams of carbohydrate per kilogram of body weight) about three to four hours before exer­cising to maximize pre-exercise glycogen stores. If the exercise is unplanned, eat 20 to 30 grams of carbohydrate immediately before you exercise.

The amount of carbohydrate that needs to be consumed will depend on the dura­tion and intensity of the exercise. Generally speaking, about 20 to 30 grams of car­bohydrate is needed for each thirty minutes of exercise. Table 9-1 provides a good starting point in determining how many grams of carbohydrate you might need every half hour for different types of exercise.

The type of carbohydrate you consume can vary:

• Before exercise, you could have fruit (apples, dried apricots), bread, yogurt, porridge, pasta, or milk. 
• During exercise, you could have a fruit juice/water mixture or sports drink. Sports drinks can give you some sodium and potassium as well as carbohydrate. Read the labels for the carbohydrate, sodium, and potassium contents. Sport gels or carbohydrate-rich bars are also good sources of rapidly absorbed carbohydrates and salts—usually, you want to drink some water with them. 
• After exercise, you can have bread, potato, rice, cereal such as cornfl akes, a granola bar, or cookies. 

Drink Fluids

Dehydration will increase your glucose levels, so you need to drink plenty of fl uids while exercising. In the two hours before exercise, drink two glasses of water, and dur­ing exercise, drink enough to replace fluid loss. For prolonged exercise such as running or cycling, drinking approximately 250 ml (8 ounces) every twenty minutes of exer­cise would be reasonable. Sport drinks are good for fluid and carbohydrate replace­ment. Avoid drinking too much fluid, because this can lead to low sodium levels.

Provide Emergency Information

Wear your MedicAlert bracelet or shoe tags, just in case you get a severe episode of hypoglycemia.