Whether you consider yourself an athlete or an occasional recreational sports participant, you benefit from any activity that you do, because all exercise can improve your body’s ability to use insulin. If you do not inject or infuse insulin to treat your diabetes, exercise should result in a decreased release of insulin by your pancreas and a more efficient uptake of blood glucose by muscle cells. If you use insulin, however, you may be concerned that exercise can complicate the normal maintenance of your blood glucose level.
Active people who use insulin need to make frequent adjustments in their diabetes regimen to maintain blood glucose in target range, especially when doing higher-intensity or longer-duration exercise. But the effort can pay off in improved blood glucose control, reduced nighttime hypoglycemia, improved cardiovascular fitness, and weight loss. When it comes to managing exercise effectively, continuous, subcutaneous insulin-infusion therapy (or more simply, insulin pump therapy) is an option to consider.
How insulin pumps work
Scientists attempting to mimic the insulin delivery of a normal, healthy pancreas first developed insulin pumps in the late 1970’s. Today’s cell-phone–size pumps are much more sophisticated and give both basal insulin doses (background insulin delivered every few minutes in small increments to cover your body’s general need for insulin) and boluses (larger doses given to cover meals and snacks or to lower elevated blood glucose at any time).
Currently, roughly 500,000 individuals with diabetes worldwide wear portable insulin pumps, and this number has been increasing each year. Most pump users have Type 1 diabetes, but some people with Type 2 diabetes who require insulin are choosing to pump insulin as well. A main advantage of insulin delivery via an insulin pump is more reliable insulin action through a constant infusion of short-acting insulin, along with precise dosing and timing of insulin to cover food intake. Many insulin pump users experience improved overall blood glucose control, reduced risk of nighttime low blood glucose, and improved awareness of low blood glucose (hypoglycemia).
Insulin pumps contain a reservoir or cartridge filled with insulin, either Regular or one of the rapid-acting insulin analogs, insulin lispro (brand name Humalog), insulin aspart (NovoLog), or insulin glulisine (Apidra). Compared to Regular insulin, these insulin analogs have a more rapid onset of activity (5 to 15 minutes versus 20 to 30 for Regular) and an earlier peak in activity (90 minutes versus 150 minutes). Their use allows for a blood glucose response following carbohydrate intake that is closer to that of a person without diabetes and for a more rapid correction of hyperglycemia (above-normal blood glucose levels).
All insulin pumps currently on the market deliver insulin subcutaneously (under the skin) in the abdomen, buttocks, legs, or upper arms, either through a needle or through a plastic infusion catheter. Pump users replace the needle or catheter infusion set every two to three days with a new set at a new site.
Pumps and exercise
Pump users with active lifestyles can experience a metabolic response to exercise that is similar to that of people who do not have diabetes. In part, this is simply because of how an insulin pump works, by delivering small amounts of fast-acting or rapid-acting insulin continually. But it also depends on the user monitoring his blood glucose level frequently, adjusting basal and bolus doses to fit the exercise, and learning from experience. (Click here to see some sample basal profiles.)