Diabetes mellitus is a lifelong condition that can be controlled with lifestyle adjustments and medical treatments. Keeping blood sugar levels under control can prevent or minimize complications. Insulin treatment is one component of a diabetes treatment plan for people with type 1 diabetes.
Insulin treatment replaces or supplements the body's own insulin, restoring normal or near-normal blood sugar levels. Many different types of insulin treatment can successfully control blood sugar levels; the best option depends upon a variety of individual factors. With a little extra planning, people with diabetes who take insulin can lead a full life and keep their blood sugar under control.
Other topics that discuss type 1 diabetes are also available. (See "Patient information: Diabetes mellitus type 1: Overview (Beyond the Basics)" and "Patient information: Self-blood glucose monitoring in diabetes mellitus (Beyond the Basics)" and "Patient information: Type 1 diabetes mellitus and diet (Beyond the Basics)" and "Patient information: Hypoglycemia (low blood sugar) in diabetes mellitus (Beyond the Basics)" and "Patient information: Care during pregnancy for women with type 1 or 2 diabetes mellitus (Beyond the Basics)".)
The pancreas produces very little or no insulin at all in people with type 1 diabetes. All patients with type 1 diabetes will eventually require insulin. Insulin must be given as a shot.
Dosing — When you are first starting insulin, it will take some time to find the right dose. A doctor or nurse will help to adjust your dose over time. It is important to check your blood sugar level several times per day during this time.
Insulin needs often change over your lifetime. Changes in weight, what you eat, health conditions (including pregnancy), activity level, and work can affect the amount of insulin needed to control your blood sugar.
Many people are able to adjust their own insulin dose, although you will need help from time to time. Most people with type 1 diabetes meet with a doctor or nurse every three to four months; you will review your blood sugar levels and insulin doses at these visits, helping to fine-tune your diabetes control. (See "Patient information: Care during pregnancy for women with type 1 or 2 diabetes mellitus (Beyond the Basics)".)
Types — There are several different types of insulin. These types are classified according to how quickly they begin working and how long the insulin lasts:
- Rapid-acting (eg, insulin lispro [Humalog®], insulin aspart [Novolog®], and insulin glulisine [Apidra®])
- Short-acting (eg, insulin regular)
- Intermediate-acting (eg, insulin NPH)
- Long-acting (eg, insulin glargine [Lantus®], insulin detemir [Levemir®])
Insulin types can be used in combination to achieve around-the-clock blood sugar control.
There are two general types of insulin treatment plans: intensive insulin treatment and standard (conventional) insulin treatment. In general, intensive insulin therapy is recommended for people with type 1 diabetes. Standard insulin treatment is an older regimen, although it may still be recommended for selected patients.
Intensive insulin treatment — Intensive insulin treatment is best for keeping blood sugar in tight control. You will need to take three or more insulin shots per day or use an insulin pump, and you will need to check your blood sugar frequently.
Intensive insulin therapy is recommended for most people with type 1 diabetes, starting as soon as possible. However, this regimen will be successful only if you are fully committed to it and you have good understanding of the regimen.
Benefits — Intensive insulin treatment can improve blood sugar control, which can improve how you feel on a daily basis as well as reduce your risk of health complications later in life .
Drawbacks — There are a few drawbacks to intensive insulin treatment:
- You will need to coordinate your daily activities, what you eat, how much and when you exercise, and you will need to check your blood sugar frequently (four or more times per day).
- There is an increased risk of low blood sugar episodes. (See "Patient information: Hypoglycemia (low blood sugar) in diabetes mellitus (Beyond the Basics)".)
- Some people gain weight initially, although exercise can counteract this effect.
- It is about three times as expensive as standard insulin treatment.
Staying motivated — Intensive treatment can be demanding and some people lose motivation over time. Your doctor or nurse can provide tips and encouragement to help you stay on track. Helpful information and support is also available from the American Diabetes Association (ADA), at 800-342-2383 and at www.diabetes.org.
Insulin is usually given as a shot into the skin (this is called a subcutaneous injection). The following figure demonstrates the sites where you can inject insulin (figure 1).
You and your parents or partner should learn to draw up and give insulin shots.
Needle and syringe — You will use a needle and syringe to draw up and inject insulin under the skin. The needle must be injected at the correct angle; injecting too deeply could deliver insulin to the muscle, where it is absorbed quickly. Injecting too shallowly deposits insulin in the skin, which is painful and prevents the body from absorbing the insulin.
The best angle for insulin injection depends upon your body type, where you are injecting, and the length of your needle. A doctor or nurse can show you the right angle of injection.
Drawing up insulin — There are many different types of syringes and needles, so it's best to get specific instructions on drawing up insulin from your doctor or nurse. Basic information is provided in the table (table 1). If you use an insulin pen, you should follow the instructions for dosing and giving insulin provided by the pen manufacturer and your doctor (see 'Insulin pen injectors' below).
Before drawing up insulin, it is important to know the dose and type of insulin needed. If more than one type of insulin is combined in one syringe, the person drawing up the insulin should calculate the total dose before drawing up the insulin. Some people, including children and those with difficulty seeing, may need assistance. Devices to magnify the syringe markings and simplify the drawing up process are available.
Injection technique — The following is a description of subcutaneous insulin injection.
- Choose the site to inject (figure 1). It is not necessary to clean the skin with alcohol unless the skin is dirty.
- Pinch up a fold of skin and quickly insert the needle at a 90º angle (or other angle, as described above) (figure 2). Keep the skin pinched to avoid injecting insulin into the muscle.
- Push the plunger down completely to inject the insulin. Hold the syringe and needle in place for five seconds.
- Release the skin fold.
- Remove the needle from the skin.
If blood or clear fluid (insulin) is seen at the injection site, apply pressure to the area for five to eight seconds. The area should not be rubbed because this can cause the insulin to be absorbed too quickly.
Needles and syringes should only be used once and then thrown away. Used needles and syringes should not be included with regular household trash, but should instead be placed in a puncture-proof container (also known as a sharps container), available from most pharmacies or hospital supply stores.
Injecting through clothing — Some people wonder about the safety of injecting insulin through their clothing. One small study examined the risks and benefits of this technique, and found that blood sugar control did not differ between the group that injected insulin through a single layer of clothing and those that injected directly into the skin . There were no reports of infections in either group, although a few people who injected through clothing reported blood stains on their clothing or bruises on the skin. If you are interested in using this technique, speak with your healthcare provider before trying it.
Insulin pen injectors — Insulin pen injectors may be more convenient to carry and use when away from home. Most are approximately the size of a large writing pen, and contain a disposable insulin cartridge and needle. Some types of insulin and some insulin mixtures are not available in cartridges, meaning that pens may not be an option for everyone.
Pens are especially useful for accurately injecting very small doses of insulin, and may be helpful for people with impaired vision. Pens are generally more expensive than traditional syringes and needles. A number of insulin pens are available, and the specific instructions for each type should be obtained from the manufacturer or a healthcare provider.
Inhaled insulin — An inhaled form of rapid-acting insulin was available for a short time but was discontinued in 2007. Other inhaled insulin preparations are in clinical trials but are not currently available.
Insulin pump — Insulin can be continuously administered by insulin pump, a process called continuous subcutaneous insulin infusion. An insulin pump may be recommended if you are willing to closely monitor your blood sugar levels, amount and type of food eaten, and other factors.
The pump is worn externally (in a pocket or on the belt) and is attached to the body with long, thin, flexible plastic tubing that has a needle or soft cannula (thin plastic tube). The cannula or needle is inserted and then left in place beneath the skin. You change the needle or cannula and tubing every 48 to 72 hours. The pump stores rapid acting insulin in a cartridge.
The pump is programmed to give a small dose of insulin continuously through the day and night. At meal times, you must program the pump to give an additional dose of insulin, based upon your blood sugar level and amount of food you plan to eat. The pump can be taken off for up to one hour without impacting blood sugar control; if it is taken off for longer periods of time, insulin injections may be needed to control the blood sugar.
The insulin pump has advantages and disadvantages; it may be helpful to talk with a person who uses a pump before deciding to try it. Most pump manufacturers have a list of people willing to speak with prospective pump users. It may also be possible to use a trial pump for a few days before committing to it.
Advantages — Insulin pumps have the advantage of flexible timing of meals and other day-to-day events, similar to intensive treatment regimens that combine very-rapid acting and long-acting insulins. This can be of great benefit for children or adults whose schedule varies from one day to the next. People who use an insulin pump do not require multiple daily injections; most patients who use the pump change their injection site every 48 to 72 hours.
The other major advantage of an insulin pump is that there is less variation in the amount of insulin absorbed compared with when insulin is given with a needle and syringe. This can help reduce day-to-day variations in blood sugar levels.
Disadvantages — The cost of an insulin pump and supplies is greater than the cost of insulin syringes and needles, although most insurance carriers cover some portion of the expenses. Some patients develop pump-associated problems, including skin infection at the injection site or pump malfunction.
You must take care to monitor your blood sugar levels carefully; stopping insulin, even for a short time, can lead to a significant increase in blood sugar. Some people find the pump awkward, unpleasant, or embarrassing. However, you can disconnect the pump for brief periods, if desired.
FACTORS AFFECTING INSULIN ACTION
Several factors can affect how insulin is absorbed.
Dose of insulin injected — The dose of insulin injected affects the rate at which your body absorbs it. For example, larger doses of insulin may be absorbed more slowly than a small dose. With larger doses of insulin, the insulin may peak later or last longer than with small doses. This could mean that your blood sugar level is higher than expected within a few hours after eating, but then becomes low.
Injection technique — The angle and depth of an insulin injection are important, as mentioned above (see 'Needle and syringe' above).
Site of injection — Clinicians usually recommend changing your injection site to minimize tissue irritation. However, it is important to keep in mind that insulin is absorbed at different rates in different areas of the body. Insulin is absorbed fastest from the abdominal area, slowest from the leg and buttock, and at an intermediate rate from the arm. This may vary with the amount of fat under the skin; the more fat, the more slowly insulin is absorbed (figure 1).
Because of variations in absorption, it is reasonable to use the same general area for injections at a particular time of the day. Pre-meal insulin injections are absorbed fastest from the abdominal area, allowing for optimal coverage of carbohydrates consumed in a meal. Injection into the thigh or buttock may be best for the evening dose because the insulin will be absorbed more slowly during the night.
Subcutaneous blood flow — Any factors that alter the rate of blood flow to the body's tissues will alter insulin absorption. Smoking actually decreases blood flow to the tissues and decreases absorption of injected insulin. In contrast, factors that increase the skin temperature (such as exercise, saunas, hot baths, and massage of the injection site) will increase insulin absorption.
Time since opening the bottle — While most insulin remains potent and effective for up to a month after the bottle has been opened (if kept in the refrigerator between injections) the potency for intermediate or long-acting insulin begins to decrease after 30 days. This can be a problem for people who require very small doses of insulin, for whom a bottle might last two months or more. It is advisable to open a new bottle at least every 30 days, even if there is insulin left in the old bottle.
For rapid-acting insulin used in pen injectors, it is acceptable to keep the pen injector unrefrigerated (in a bag or jacket pocket) for up to 14 days, provided that the pen is not exposed to very warm or cold conditions. However, after 14 days, a new insulin cartridge or pen should be used, even if there is insulin left in the old cartridge.
Individual factors — The same dose of the same type of insulin may have different effects in different people with diabetes. Some trial and error is usually necessary to find the ideal type(s) and dose of insulin and schedule for each person.
Several special situations can complicate insulin treatment. With advance planning and close monitoring, these situations are less likely to cause serious difficulties. A healthcare provider can help to handle these situations.
Eating out — Eating out can be challenging since ingredients used, calorie and fat content, and portion sizes are usually different from meals prepared at home. You can estimate the carbohydrate content of meals to calculate insulin dose; nutrition information is often available from restaurants or a hand-held reference book.
Low or high blood sugar levels can occur more easily in situations where new or different foods are eaten; a fast-acting source of carbohydrates (eg, candy, glucose tablets) and a blood glucose monitor should be kept on hand at all times. (See "Patient information: Type 1 diabetes mellitus and diet (Beyond the Basics)".)
Surgery — Patients who have surgery may be instructed not to eat for 8 to 12 hours before their procedure. A healthcare provider can help to determine the dose and timing of insulin before and after the procedure, especially if you will be unable to eat a normal diet afterwards.
Infections — Mild infections, such as a cold, sore throat, or urinary tract infection, can cause blood sugar levels to rise and can even lead to diabetic ketoacidosis. In this situation, frequent telephone contact with a healthcare provider, careful blood sugar monitoring, and increasing the insulin dose are often recommended. Patients with nausea or vomiting may require medication to control their symptoms and avoid dehydration and ketoacidosis. If dehydration occurs, treatment with intravenous (IV) fluids may be necessary.
Travel — Managing blood sugar levels and insulin treatment while traveling can be difficult, especially when traveling across multiple time zones. In addition, activity levels and diet are often different while traveling, making careful blood sugar monitoring essential. Speak with your healthcare provider before traveling to develop a treatment plan. (See "Patient information: General travel advice (Beyond the Basics)", section on 'Traveling with medical conditions'.)
WHERE TO GET MORE INFORMATION
Your healthcare provider is the best source of information for questions and concerns related to your medical problem.
This article will be updated as needed on our web site (www.uptodate.com/patients). Related topics for patients, as well as selected articles written for healthcare professionals, are also available. Some of the most relevant are listed below.
Patient level information — UpToDate offers two types of patient education materials.
The Basics — The Basics patient education pieces answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials.
Patient information: Type 1 diabetes (The Basics)
Patient information: Using insulin (The Basics)
Patient information: Should I switch to an insulin pump? (The Basics)
Patient information: Low blood sugar in people with diabetes (The Basics)
Patient information: Care during pregnancy for women with type 1 or type 2 diabetes (The Basics)
Patient information: My child has diabetes: How will we manage? (The Basics)
Patient information: Keeping your child’s blood sugar under control (The Basics)
Patient information: Managing diabetes in school (The Basics)
Patient information: Giving your child insulin (The Basics)
Patient information: Checking your child’s blood sugar level (The Basics)
Patient information: Carb counting and your child’s diet (The Basics)
Patient information: Diabetic ketoacidosis (The Basics)
Beyond the Basics — Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are best for patients who want in-depth information and are comfortable with some medical jargon.
Patient information: Diabetes mellitus type 1: Overview (Beyond the Basics)
Patient information: Self-blood glucose monitoring in diabetes mellitus (Beyond the Basics)
Patient information: Type 1 diabetes mellitus and diet (Beyond the Basics)
Patient information: Hypoglycemia (low blood sugar) in diabetes mellitus (Beyond the Basics)
Patient information: Care during pregnancy for women with type 1 or 2 diabetes mellitus (Beyond the Basics)
Patient information: General travel advice (Beyond the Basics)
Professional level information — Professional level articles are designed to keep doctors and other health professionals up-to-date on the latest medical findings. These articles are thorough, long, and complex, and they contain multiple references to the research on which they are based. Professional level articles are best for people who are comfortable with a lot of medical terminology and who want to read the same materials their doctors are reading.
Effects of exercise in diabetes mellitus in adults
Estimation of blood glucose control in diabetes mellitus
General principles of insulin therapy in diabetes mellitus
Glycemic control and vascular complications in type 1 diabetes mellitus
Medical management of type 1 and type 2 diabetes mellitus in pregnant women
Inhaled insulin therapy in diabetes mellitus
Insulin therapy in adults with type 1 diabetes mellitus
Management of hypoglycemia during treatment of diabetes mellitus
Nutritional considerations in type 1 diabetes mellitus
Overview of medical care in adults with diabetes mellitus
Pancreas and islet transplantation in diabetes mellitus
Perioperative management of diabetes mellitus
Prevention of type 1 diabetes mellitus
The adult patient with brittle diabetes mellitus
The following organizations also provide reliable health information.
- National Library of Medicine
- National Institute of Diabetes and Digestive and Kidney Diseases
- American Diabetes Association (ADA)
- Canadian Diabetes Associates
- Juvenile Diabetes Research Foundation
- US Center for Disease Control and Prevention