If you have diabetes, taking medicines is a major part of staying healthy because
they help keep your blood sugar levels under control. Having blood sugar that's out
of control can make you feel awful and can damage your body over the years.
Whether you have type 1 or type 2 diabetes, it's important to know
what medicine to take, when to take it, and how much to take.
What Is Insulin?

Insulin is a hormone that lets sugar, or glucose, get into the body's cells where
it can be used for energy. All people with type 1 diabetes and many people with type
2 diabetes need to take insulin every day.
The overall goal of treatment with insulin (and other diabetes medicines) is to
match the amount of insulin given with the amount of insulin a person needs throughout
the day and night. Doing this means that blood sugar levels can be kept as close to
normal as possible, which helps a person avoid both short- and long-term problems
from diabetes.
The types of insulin you use and how much you need to take each day depends on
your diabetes management plan. Some people with diabetes need to take two injections
each day. Others may need several injections or an insulin pump to keep blood sugar
levels under control. Your doctor will help you decide what's best for you.
There are a few different kinds of insulin. They differ from one another based
on:
- how long they take to start working
- when they work their hardest to lower blood sugar
- how long they last
The table below outlines the types of insulin and how they work. The time it takes
for insulin to work, when it peaks, and how long it lasts is different from person
to person, and even from day to day as the way a person's body reacts to insulin may
change. After a while, you'll get to know how insulin works in your body.
Rapid-Acting Insulin
When It Starts Working: 10–15 minutes
When It Works Hardest: 30–90
minutes
How Long It Lasts: 4 hours
How It Works: Used to help your
body handle glucose that you absorb when eating a meal. For the best results, it is
usually taken several minutes before or just before eating. Looks clear and can be
mixed with intermediate-acting insulin in the same syringe.
Short-Acting Insulin
When It Starts Working: 30–60 minutes
When It Works Hardest: 2–4
hours
How Long It Lasts: 6–9 hours
How It Works: Used to help
your body handle glucose that you absorb when eating a meal, but lasts longer than
rapid-acting insulin. Take it 30 minutes before eating. Looks clear and can be mixed
with intermediate-acting insulin in the same syringe.
Intermediate-Acting Insulin
When It Starts Working: 1–4 hours
When It Works Hardest: 3–14
hours
How Long It Lasts: 10–24 hours
How It Works: Works to control
glucose between meals and during the night. Looks cloudy or and can be mixed with
rapid- and short-acting insulin in same syringe.
Long-Acting Insulin
When It Starts Working: 1–2 hours
When It Works Hardest: does
not peak
How Long It Lasts: 18–24 hours
How It Works: Works to
control glucose between meals and during the night. Looks cloudy or clear and can't
be mixed with other insulin in the same syringe.
The Importance of Timing
You can't "turn off" insulin once it's been injected — it's going to work
no matter what — so you have to make sure you're using the right amount at the
right time. For example, if you'll be eating later than usual because you're eating
out, you might need to hold off on your insulin injection, eat a small snack at your
normal mealtime, and take the insulin later.
Sticking to a meal plan from day to day and getting regular physical activity —
in addition to taking your meds — will help you keep your blood sugar levels
in a healthy range and will make it easier to know how much insulin to take. If you
run into situations where you're not sure how to adjust your insulin dosage to account
for food or exercise, ask a parent or a member of your diabetes
health care team.
Although you may do everything you're supposed to, sometimes blood sugar is hard
to control. For people with diabetes, there will be times when the amount of insulin
they have taken will be too much or too little for the body's needs and the blood
sugar level will be too high or
too low.
A common problem among people who take insulin is low
blood sugar, or hypoglycemia. It can happen at any time, but is more likely if
someone eats less or exercises more than usual. Hypoglycemia is also more likely in
the first few weeks or months after a person develops type 1 diabetes.
If your blood sugar goes too low regularly, it may mean that your insulin dose
or meal plan needs adjusting. If this happens, contact your diabetes health care team.
They'll help you develop a plan to help keep your blood sugar levels as close to normal
as possible.
Tips for Using Insulin
Insulin can't be taken as a pill because the acids and digestive juices in the
stomach and intestines would destroy it before it could do its job. The only way to
get insulin into the body at present is by injection with a needle or with an insulin
pump.
Before giving yourself an insulin injection, always check the bottle to make sure
you're using the right type of insulin and that it hasn't expired. You should also
inspect the bottle to see if the insulin looks OK — for example, it should not
have particles or crystals floating in it. If you have any questions about whether
the insulin is OK to use, ask a parent or your doctor about it.
Here are some guidelines on storing bottled insulin (check manufacturer's instructions
for storage of insulin pens):
- Keep unopened bottles of insulin in the refrigerator. Throw away insulin if it
has been frozen or is past the expiration date on the bottle.
- Opened bottles of insulin can be stored in the refrigerator or kept at room
temperature.
- Avoid leaving insulin in direct sunlight or in a car on a sunny or hot day because
it can become overheated. If you're going to be traveling or outdoors, store insulin
as you would perishable food (but do not freeze it).
- Depending on the type of insulin, opened bottles should be thrown away after 4
to 6 weeks (check manufacturer's instructions), whether they have been kept refrigerated
or not.
- Never use any insulin that has expired.