Living with diabetes

Important details for sport

During physical activity the need for insulin decreases. The quantities of carbohydrates and insulin must be adjusted accordingly in order to avoid hypos. Unfortunately, no exact formula can be given, as this depends on many factors, such as the initial blood sugar level, insulin levels in the body, physical fitness level, and the intensity and duration of the physical activity. However, as a rule of thumb you should pay attention to the following:

Before starting any physical activity:

• Definitely check your blood sugar level!


• If your current blood sugar level is less than 150 mg/dL (8.3 mmol/L), then there is a danger that you will experience a hypo during the physical activity. Before you start the activity you should therefore boost your blood sugar level above this value by eating more carbohydrates.


• If your blood sugar is more than 250 mg/dL (13.9 mmol/L), or more than 200 mg/dL (11.1 mmol/L) if you carry an insulin pump, then you must perform an acetone test! If it is positive then there is an insulin deficiency. You may under no circumstances participate in the physical activity.

For short periods of physical activity (for 1 to 2 hours):

• Balance the decreased insulin requirement by eating more carbohydrates.

For longer periods of physical activity (for 3 to 4 hours):

• Reduce the background rate and peak insulin during this period to about 70%.


• If you carry a pump, you should program the reduction of the background rate at least two hours (if using normal insulin) or one hour (lispro insulin) before beginning the physical activity.


• If you carry a pump, it is generally not a problem to remove the pump for 3 to 4 hours (normal insulin) or 1 to 2 hours (short-acting insulin analogues). However, during this period you should remember to check your blood sugar level every 1 to 2 hours.

All-day exercise with the use of an insulin pump:

• Reduce the background rate and peak insulin to about 50%.


• Cover the increased energy requirement by eating more carbohydrates.


• Keep the background rate at the lowered rate of 50% throughout the following night as well.

After the physical stress has ended your insulin requirement remains lower for some time. This is because the muscle tissue tries to refill its sugar reserves, and in doing so absorbs a great deal of sugar out of the blood (muscle refill effect).
You should therefore:

• check your blood sugar level frequently


• reduce the insulin delivery rate and/or eat additional carbohydrates
  The muscle refill effect can last a number of hours, or even for some days in extreme cases.
  

It is frequently forgotten that physical activity does not just involve sport. Daily activities, such as gardening, shopping, cleaning windows or going for a walk, also reduce the body’s insulin requirements.