Getting just the right amount of insulin can be a daily balancing act.
If you take too much, you risk a potentially dangerous episode of hypoglycemia. But if you don't take enough, your blood sugar can get too high and over time, you run the risk of serious complications. How insulin works in your body depends on a number of factors, too.
Here's a guide to what affects it:
1. The site of the injection
Insulin is absorbed most quickly when injected into the abdomen, followed by the upper arms, says Emily Coppedge, diabetes educator at NewYork-Presbyterian Hospital/Columbia University Medical Center in New York City. Injecting into the legs or the buttocks means the insulin will get absorbed more slowly, she says. But if you inject in the same site all the time, you'll develop scar tissue that can result in delayed absorption of the insulin. "It's important to rotate sites so this doesn't happen," Coppedge says. Similarly, insulin is absorbed faster when injected in a muscle you are using. For example, you may want to inject your insulin into the abdomen instead of the arm if you are planning on raking leaves or shoveling snow.
2. Type of insulin
Ideally, you want your insulin to start working at its peak right when your food is being digested. "Some of the short-acting insulins work within 30 minutes, and then there are longer-acting ones that work in 9 to 24 hours," says Asha Thomas, MD, medical director of the Division of Endocrinology at Sinai Hospital in Baltimore.
3. Exercise
When you exercise, you're more sensitive to insulin, Thomas explains. "This is why people may feel like their blood sugar is going down during exercise," she says. "There are two things going on at once. As your muscles work and use the insulin, the tissues of the body also may be more efficient at using insulin." While exercising can signify that you need less insulin, occasionally very intense exercise increases blood sugar and may cause you to need even more insulin.
4. Temperature
"Heat can definitely affect your blood sugar," Coppedge says. Insulin enters your system quicker when your muscles are warm than when they are at a normal temperature. So if you just took a bath, it will kick in more quickly than if you were out jogging in chilly temperatures. If you want your insulin to be absorbed more slowly, cooling the injection site with a cold pack may be effective.
5. Stress and illness
Both of these can raise your blood sugar, Coppedge says. When you are stressed, your body releases certain hormones that can actually keep your body from producing sufficient insulin or using it effectively. Individuals with diabetes who have gastroparesis (a digestive disorder) may not digest their food properly. "Because their GI tract isn't working correctly, these patients who receive insulin can become hypoglycemic," Thomas says.
6. Dehydration
If you don't drink sufficient water, you may not absorb insulin as quickly. And dehydration increases blood sugar, even causing a short-term resistance to insulin.
