Health Guide
Drug Guide

Insulin (Parenteral route)

Uses of This Medicine:

Insulin is one of many hormones that helps the body turn the food we eat into energy. Also, insulin helps us store energy that we can use later. After we eat, insulin works by causing sugar (glucose) to go from the blood into our body's cells to make fat, sugar, and protein. When we need more energy between meals, insulin will help us use the fat, sugar, and protein that we have stored. This occurs whether we make our own insulin in the pancreas gland or take it by injection.

Diabetes mellitus (sugar diabetes) is a condition in which the body does not make enough insulin to meet its needs or does not properly use the insulin it makes. Without insulin, glucose cannot get into the body's cells. Without glucose, the cells will not work properly.

To work properly, the amount of insulin you use must be balanced against the amount and type of food you eat and the amount of exercise you do. If you change your diet, your exercise, or both without changing your insulin dose, your blood glucose level can drop too low or rise too high. A prescription is not necessary to purchase most insulin. However, your doctor must first determine your insulin needs and provide you with special instructions for control of your diabetes

Insulin can be obtained from beef or pork pancreas glands. Another type of insulin that you may use is called human insulin. It is just like the insulin made by humans but it is made by methods called semi-synthetic or recombinant DNA. All types of insulin must be injected because, if taken by mouth, insulin is destroyed in the stomach.

Insulin is available only with your doctor's prescription.

Once a medicine has been approved for marketing for a certain use, experience may show that it is also useful for other medical problems. Although this use is not included in product labeling, regular insulin is used in certain patients with the following medical conditions:

Before Using This Medicine:


Tell your doctor if you have ever had any unusual or allergic reaction to medicines in this group or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.


Children are especially sensitive to the effects of insulin before puberty (the time when sexual changes occur). Therefore, low blood sugar may be especially likely to occur.

Use in teenagers is similar to use in older age groups. The insulin need may be higher during puberty and lower after puberty.

Older adults

Use in older adults is similar to use in other age groups. However, sometimes the first signs of low or high blood sugar are missing or not easily seen in older patients. This may increase the chance of low blood sugar during treatment. Also, some older people may have vision problems or other medical problems that make it harder for them to measure and inject the medicine. Special training and equipment may be needed.


The amount of insulin you need changes during and after pregnancy. It is especially important for your health and your baby's health that your blood sugar be closely controlled. Close control of your blood sugar can reduce the chance of your baby gaining too much weight, having birth defects, or having high or low blood sugar. Be sure to tell your doctor if you plan to become pregnant or if you think you are pregnant.


Insulin does not pass into breast milk and will not affect the nursing infant. However, most women need less insulin while breast-feeding than they needed before. You will need to test your blood sugar often for several months in case your insulin dose needs to be changed.

Other medicines

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking any of these medicines, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using medicines in this class with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

Other interactions

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using medicines in this class with any of the following is usually not recommended, but may be unavoidable in some cases. If used together, your doctor may change the dose or how often you use your medicine, or give you special instructions about the use of food, alcohol, or tobacco.

Other medical problems

The presence of other medical problems may affect the use of medicines in this class. Make sure you tell your doctor if you have any other medical problems, especially:

Proper Use of This Medicine:

Make sure you have the type (beef and pork, pork, or human) and the strength of insulin that your doctor ordered for you. You may find that keeping an insulin label with you is helpful when buying insulin supplies.

The concentration (strength) of insulin is measured in USP Insulin Units and USP Insulin Human Units and is usually expressed in terms such as U-100 insulin. Insulin doses are measured and injected with specially marked insulin syringes. The appropriate syringe is chosen based on your insulin dose to make measuring the dose easy to read. This helps you measure your dose accurately. These syringes come in three sizes: 3/10 cubic centimeters (cc) measuring up to 30 USP Units of insulin, ½ cc measuring up to 50 USP Units of insulin, and 1 cc measuring up to 100 USP Units of insulin.

It is important to follow any instructions from your doctor about the careful selection and rotation of injection sites on your body.

There are several important steps that will help you successfully prepare your insulin injection. To draw the insulin up into the syringe correctly, you need to follow these steps:

How to prepare your insulin dose if you are using one type of insulin:

How to prepare your insulin dose if you are using two types of insulin:

How to inject your insulin dose:

How to use special injection devices:

For patients using an automatic injector (with a disposable syringe):

For patients using a continuous subcutaneous infusion insulin pump:

For patients using disposable syringes:

For patients using an insulin pen device (cartridge and disposable needles):

For patients using nondisposable syringes (glass syringe and metal needle):

For patients using a spray injector (device without needles):

Laws in some states require that used insulin syringes and needles be destroyed. Be careful when you recap, bend, or break a needle, because these actions increase the chances of a needle-stick injury. It is best to put used syringes and needles in a disposable container that is puncture-resistant (such as an empty plastic liquid laundry detergent or bleach bottle) or to use a needle-clipping device. The chance of a syringe being reused by someone else is smaller if the plunger is taken out of the barrel and broken in half when you dispose of a syringe.

Use this medicine only as directed. Do not use more or less insulin than recommended by your doctor. To do so may increase the chance of serious side effects.

Your doctor will give you instructions about diet, exercise, how to test your blood sugar levels, and how to adjust your dose when you are sick.


The dose medicines in this class will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of these medicines. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.


Store in the refrigerator. Do not freeze.

Unopened bottles of insulin should be refrigerated until needed and may be used until the printed expiration date on the label. Insulin should never be frozen. Remove the insulin from the refrigerator and allow it to reach room temperature before injecting it.

An insulin bottle in use may be kept at room temperature for up to 1 month. Insulin that has been kept at room temperature for longer than a month should be thrown away.

Storing prefilled syringes in the refrigerator with the needle pointed up reduces problems that can occur, such as crystals forming in the needle and blocking it up.

Do not expose insulin to extremely hot temperatures or to sunlight. Extreme heat will cause insulin to become less effective much more quickly.

Precautions While Using This Medicine:

Never share insulin pens or cartridges with others under any circumstances. It is not safe for one pen to be used for more than one person. Sharing needles or pens can result in transmission of hepatitis viruses, HIV, or other blood-borne illnesses.

It is very important that your doctor check your progress at regular visits, especially during the first few weeks of insulin treatment.

It is very important to follow carefully any instructions from your health care team about:

In case of emergency There may be a time when you need emergency help for a problem caused by your diabetes. You need to be prepared for these emergencies. It is a good idea to:

Too much insulin can cause low blood sugar (also called hypoglycemia or insulin reaction). Symptoms of low blood sugar must be treated before they lead to unconsciousness (passing out). Different people may feel different symptoms of low blood sugar. It is important that you learn what symptoms of low blood sugar you usually have so that you can treat it quickly.

High blood sugar (hyperglycemia) is another problem related to uncontrolled diabetes. If you have any symptoms of high blood sugar, contact your health care team right away. If high blood sugar is not treated, severe hyperglycemia can occur, leading to ketoacidosis (diabetic coma) and death.

Side Effects of This Medicine:

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

More common
Convulsions (seizures)

Check with your doctor as soon as possible if any of the following side effects occur:

More common
Low blood sugar (mild), including anxious feeling, behavior change similar to being drunk, blurred vision, cold sweats, confusion, cool pale skin, difficulty in concentrating, drowsiness, excessive hunger, fast heartbeat, headache, nausea, nervousness, nightmares, restless sleep, shakiness, slurred speech, unusual tiredness or weakness
weight gain
Depressed skin at the place of injection
swelling of face, fingers, feet, or ankles
thickening of the skin at the place of injection

Not all of the side effects listed above have been reported for each of these medicines, but they have been reported for at least one of them. All of the insulins are similar, so any of the above side effects may occur with any of these medicines.

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Last Updated: 10/12/2016

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