Some possible drawbacks of insulin pump use with exercise are important to know about. Excessive sweating can cause your subcutaneous infusion set to dislodge, which may result in elevated blood glucose or ketoacidosis if you fail to notice the displacement for some time. To prevent infusion set displacement due to sweating, try using a liquid skin preparation such as Skin-Tac-H to anchor the set more firmly to your skin, or apply additional tape below the infusion set. You can also apply antiperspirant to your skin around the infusion site to minimize sweating beneath it. Or you can try wearing the infusion set in an area of the body that experiences less movement with activity, such as the buttocks. A potential problem for those using metal needles is irritation of the infusion site as a result of movement or contact. Flexible plastic infusion sets do not cause this problem.
Especially when you exercise vigorously, you must adhere to the recommendation to replace your insulin infusion set every two to three days to prevent displacement or irritation at the insertion site. It is also recommended that you check the integrity of your infusion site following vigorous exercise, sweating, or water contact.
Another potential problem is that insulin is temperature-sensitive. Exercise in hot or cold environments can potentially cause insulin to degrade and lose effectiveness. When an insulin pump is placed close to your body during exercise in the heat, the insulin may become overheated; if the pump is placed outside your clothing in the cold, the insulin may freeze. If unexpected high blood glucose arises following such conditions, replace both the infusion set and the insulin in the reservoir as a precaution.
Especially with the use of rapid-acting insulin analogs in your pump, DKA can begin as few as five hours following the displacement of your infusion set. When you become insulin-deficient due to any interruption of insulin delivery, exercise can exacerbate this situation and cause DKA to occur even more rapidly. Due to the severity of DKA, insulin pump users must be especially vigilant about maintaining the integrity of their infusion sites during exercise to prevent it from occurring.
In general, pump users should replace their entire cartridge and infusion set at the first sign of any unanticipated high blood glucose that does not respond to additional boluses.
Maintaining blood glucose control
To keep your blood glucose in the target range during and after exercise, follow some basic guidelines:
Understand the nature of the activity. Some activities, such as weight lifting, use mainly anaerobic energy sources and can have a markedly different effect on blood glucose level than prolonged or moderate-intensity aerobic exercise such as walking. Short-term, high-intensity anaerobic exercise can stimulate hormones that counteract the effects of insulin and often cause an increase in blood glucose level that can last for an hour or more after exercise. Mild to moderate aerobic exercise, on the other hand, tends to cause a decrease in blood glucose level.
Predict your blood glucose response and make regimen changes. Based on the type of activity you do, time of day you exercise, and amount and timing of your insulin delivery, you can often predict the effect of exercise on your blood glucose level and make appropriate changes. Of paramount importance are the length and intensity of the exercise and your training level.
Establish your pattern. Each time you try a new activity, check your blood glucose level frequently (before, during, and several times after an activity) to establish your usual response to the exercise, as well as variations from your predicted response.
Learn from the past. Make regimen changes (increased carbohydrate consumption and/or decreased insulin) based on your previous blood glucose response to an activity. You may also make regimen changes based on whether physical fitness or weight loss is a goal of the exercise. If you want to train hard and frequently for fitness, you will have to eat to replace the calories you are using. If weight loss is your goal, you may want to lower your insulin doses (instead of snacking) to maintain blood glucose control.