Note: This article does not refer to long-acting insulin types. For information on how to best use your insulin type, consult your doctor.
Insulin is a life-saving drug that can take over or supplement the role of natural insulin, which normally controls blood sugar.
However, taking insulin can be tricky. A surprising number of factors can affect the drug's ability to reduce blood sugar.
If you're on insulin, here are some questions you should ask yourself to help determine the impact of this powerful medication.
How much did you inject?
It's not uncommon for a doctor to make small changes in insulin to find the dose that works best. Your age, weight, eating patterns, activity and overall health can all affect the amount you need.
If you take too much you can risk hypoglycemia (when blood sugar is dangerously low) while too little means blood sugar will be too high.
Pricking your finger and testing the blood with a glucose monitor can help you figure out if you're taking the right amount.
Where did you inject it?
Insulin acts the fastest when injected into your abdomen--just above and to the side of your belly button.
Insulin gets into your system a bit slower when injected in the upper arms, even more slowly in the legs, and slowest from the buttocks.
For best results, inject in the same general area before each meal. For example, you can inject in the abdomen at breakfast and the thigh before dinner.
Make sure not to inject in exactly the same spot each time, however, as scar tissue could build up and affect insulin absorption.
More from Health.com:
What time did you inject?
Insulin is often taken just before eating (though it depends on the type) because it works best when the glucose from food starts to enter your blood.
"You want insulin to be coming up to its peak right when your food is being digested," says Christine Tobin, RN, a certified diabetes educator (CDE) and the president of health care and education at the American Diabetes Association.
Depending on the onset and duration of your insulin, experts recommend you inject either right before eating or 20 to 30 minutes before a meal.
Did you exercise?
Exercise can make you more sensitive to insulin, and you may need less of the drug. However, it's not that simple--sometimes intense exercise will cause blood sugar to go up, meaning you may need more insulin.
Exercising can also increase the absorption rate. "Depending on what you do and where you inject, if you did inject [near] the exercised muscle, you would get a different kind of release of the insulin," says Tobin.
It can take some trial and error to figure out how exercise influences your need for insulin.
Are you feeling sick?
If you are sick, your blood sugar tends to rise higher than normal.
Also, many people don't feel hungry when they're sick and eat less, "so they think they don't need their insulin," says Tobin. "When you have an illness you may require more insulin."
Be sure to continue taking insulin unless your doctor says otherwise.
The hormones released when you feel stressed can directly alter the levels of glucose in your blood and stop your body from producing enough insulin or using it properly.
"Any kind of stress on the body, even psychological stress, will raise people's blood sugars," says Tobin, "so it's not uncommon that they require more insulin during those times."
How hot is it?
If you've just stepped out of a hot shower or you've been using a heating pad on a sore muscle, insulin will get into your system faster than it would when muscles are at normal temperatures.
Some experts even suggest cooling the injection site with cold packs or ice to slow absorption if necessary.
Did you drink enough water?
If your body does not have enough water, blood doesn't flow as easily to your skin, so insulin may not be absorbed as quickly.
Dehydration also tends to raise blood sugar and can cause temporary resistance to insulin.
What are you eating?
Food won't change the rate at which insulin is absorbed into the blood, but it does affect your blood sugar in general.
Fatty foods are absorbed slowly, and your insulin may start to wear off before the food is absorbed.
Carbohydrate-rich foods like white rice or white bread that have a higher glycemic index are absorbed faster and may affect your blood sugar more quickly.
Like everyone else, people with diabetes should eat breakfast, lunch and dinner, and snacks in between, says Tobin. "It's just a little trickier for people with diabetes. Consistency of protein and carbohydrates and the timing of foods are important."