Patient education: Diabetes mellitus type 1: Insulin treatment (Beyond the Basics)
- David K McCulloch, MD
David K McCulloch, MD
- Washington Permanente Medical Group
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 with the goal of preventing ketosis and diabetic ketoacidosis and achieving 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 education: Diabetes mellitus type 1: Overview (Beyond the Basics)" and "Patient education: Self-blood glucose monitoring in diabetes mellitus (Beyond the Basics)" and "Patient education: Type 1 diabetes mellitus and diet (Beyond the Basics)" and "Patient education: Hypoglycemia (low blood sugar) in diabetes mellitus (Beyond the Basics)" and "Patient education: 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 is given under the skin, either as a shot or continuously with an insulin pump.
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. You will be instructed to check your blood sugar level several times per day.
Insulin needs often change over your lifetime. Changes in weight, what you eat, health status (including pregnancy), activity level, and work can affect the amount of insulin needed to control your blood sugar.
Most people adjust their own insulin doses, although you will need help from time to time. Meetings with a doctor or nurse will usually be scheduled 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 education: 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 [brand name: Humalog], insulin aspart [brand name: NovoLog], and insulin glulisine [brand name: Apidra])
●Short acting (eg, insulin regular)
●Intermediate acting (eg, insulin NPH)
●Long acting (eg, insulin glargine [sample brand names: Lantus and Basaglar], insulin detemir [brand name: Levemir], insulin degludec [brand name: Tresiba])
Most insulins are supplied in a concentration of 100 units per milliliter. There are also more concentrated forms of insulin that can be used to control hyperglycemia in severely insulin-resistant patients.
Insulin types are used in various combinations to achieve around-the-clock blood sugar control in type 1 diabetes.
Current-day insulin treatment plans are designed to imitate how the nondiabetic pancreas works. These plans are known as intensive insulin treatment, in contrast to older "standard" (conventional) insulin treatment. Intensive insulin therapy is recommended for most people with type 1 diabetes, although simpler standard insulin treatments may still be recommended for selected patients.
Intensive insulin treatment — Intensive insulin treatment is best for keeping blood sugar in near-normal or "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. Your personal blood sugar goals will be determined by your treatment team to make sure that you are achieving blood sugar levels that are as close to the nondiabetic range as safely possible, while minimizing hypoglycemia (low blood sugar) events. Your insulin treatment regimen will need to be realistic, taking into account your work or school schedules, eating times and preferences, and exercise schedule.
Intensive insulin therapy is recommended for most people with type 1 diabetes, starting as soon as possible after diagnosis. However, this regimen will be successful only if you are fully committed to it and you have a good understanding of the regimen. The different intensive treatment regimens all provide some insulin as a "basal" supply, which is meant to provide insulin supply at low levels throughout the day and night. The rest of the insulin is given before meals, so-called "bolus" or prandial insulin, which is given at the time of meals and keeps your blood sugar levels in control after eating.
Benefits — Intensive insulin treatment is aimed at improved blood sugar control, which has been shown to improve how you feel on a daily basis and 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, and 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 education: Hypoglycemia (low blood sugar) in diabetes mellitus (Beyond the Basics)".)
●Some people gain weight initially, although exercise can counteract this effect.
●It is often more expensive than standard insulin treatment, although most states require insurance to cover the testing and treatment supplies that are necessary.
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.
Insulin is given as a shot into the skin (this is called a subcutaneous injection) or with insulin pumps that use a small tube, called a catheter, to give the insulin into the skin (see 'Insulin pump' below). 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. Infants and very young children may need their parents to give insulin, but most older children can give themselves injections.
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 may be absorbed too quickly. Injecting too shallowly deposits insulin in the skin, which is painful and reduces complete absorption.
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 is 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 young children and those with difficulty seeing, may need assistance. Devices to magnify the syringe markings and simplify the drawing up process are available.
One type of insulin, called U-500 insulin, requires a special U-500 syringe; this syringe makes it easier to measure the right dose. If you use this type of insulin, your doctor or pharmacist can show you how to use the U-500 syringe. It is very important to use this specially marked syringe only for U-500 insulin. Using a U-500 syringe with other insulins or using a U-100 syringe with U-500 can potentially result in dangerous errors in insulin dose.
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 90° 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. Needles and syringes should never be shared. 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 health care provider before trying it.
Insulin pen injectors — Insulin pen injectors, known as insulin pens, 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 health care provider. Insulin pen cartridges should never be shared, even if the needle is changed.
Inhaled insulin — An inhaled form of rapid-acting insulin was available for a short time but was discontinued in 2007. In 2015, another formulation of inhaled insulin (brand name: Afrezza) became available for clinical use in the United States. Once inhaled, it begins to work quickly, similar to rapid-acting insulin, and is therefore considered a prandial (mealtime) insulin. Inhaled insulin has not been shown to lower glycated hemoglobin (A1C) levels to the usual target level of less than 7 percent in most studies. In addition, lung function testing is required before starting it and periodically during therapy.
General principles — Insulin can be continuously administered by insulin pump, rather than through multiple daily injections with a pen injector or needle and syringe. An insulin pump may be recommended based on your preference and willingness and ability to use it.
Most pumps deliver insulin through a long spaghetti-like catheter, the end of which you insert under the skin. The catheter is taken out and re-inserted approximately every three days. You will be taught how to do this relatively painless and quick procedure. Other pumps are entirely self-contained, with a small catheter built right into the small, disposable pump unit. These pumps are replaced every five or so days.
The pump stores rapid-acting insulin in a cartridge. 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.
Pumps are programmed to give a small dose of insulin continuously through the day and night (basal insulin). People with an insulin pump may need to check their blood sugar levels four to seven times daily (before breakfast, mid-morning, before lunch, mid-afternoon, before the evening meal, before bedtime, and occasionally at 3 AM) while their doses are being adjusted. After doses are programmed initially, testing four times per day, including before meals, is required as you must program the pump to give pre-meal insulin based upon your blood sugar level and amount and type of food you plan to eat.
The insulin pump is sometimes used in conjunction with a continuous glucose monitoring (CGM) device, which gives you more information about blood glucose levels than traditional fingersticks and a glucose meter. These devices may allow you to make better informed decisions about insulin dosing based on the blood sugar trends. Other devices automatically adjust the basal rate of insulin delivery depending on the CGM results ("artificial pancreas"). These devices can improve or maintain glucose control with less risk of hypoglycemia.
The following devices, combining an insulin pump with CGM, are available or will become available in the future:
●Sensor-augmented insulin pump – With this device, you use the CGM readings to make adjustments in the insulin dosing. The insulin pump can be programmed to stop insulin delivery for up to two hours at a preset glucose value ("low glucose suspend" feature). This feature reduces the frequency and duration of hypoglycemia that may occur while you are sleeping.
●Partially automated insulin pump (hybrid system) – The partially automated insulin pump is a hybrid system (not fully automated) in that only the basal insulin doses are automatically adjusted depending on CGM results. You need to manually request insulin doses prior to meals.
●Fully automated bihormonal insulin pump – The bihormonal system uses two commercially available pumps, with one delivering insulin and the other glucagon. The system is fully automated, in that the delivery of the insulin and glucagon is determined completely automatically by an algorithm that is, in turn, dependent on CGM results. These devices have not yet been approved and are not commercially available.
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 increasing flexibility in the timing of meals and other day-to-day events. 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 health care 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 handheld 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 education: 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 health care 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 health care 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 health care provider before traveling to develop a treatment plan. (See "Patient education: General travel advice (Beyond the Basics)", section on 'Traveling with medical conditions'.)
WHERE TO GET MORE INFORMATION
Your health care 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 website (www.uptodate.com/patients). Related topics for patients, as well as selected articles written for health care 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 education: Type 1 diabetes (The Basics)
Patient education: Using insulin (The Basics)
Patient education: Should I switch to an insulin pump? (The Basics)
Patient education: Low blood sugar in people with diabetes (The Basics)
Patient education: Care during pregnancy for women with type 1 or type 2 diabetes (The Basics)
Patient education: My child has diabetes: How will we manage? (The Basics)
Patient education: Keeping your child's blood sugar under control (The Basics)
Patient education: Managing diabetes in school (The Basics)
Patient education: Giving your child insulin (The Basics)
Patient education: Checking your child's blood sugar level (The Basics)
Patient education: Carb counting for children with diabetes (The Basics)
Patient education: 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 education: Diabetes mellitus type 1: Overview (Beyond the Basics)
Patient education: Self-blood glucose monitoring in diabetes mellitus (Beyond the Basics)
Patient education: Type 1 diabetes mellitus and diet (Beyond the Basics)
Patient education: Hypoglycemia (low blood sugar) in diabetes mellitus (Beyond the Basics)
Patient education: Care during pregnancy for women with type 1 or 2 diabetes mellitus (Beyond the Basics)
Patient education: 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 adults with diabetes mellitus
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
Pregestational diabetes mellitus: Glycemic control during pregnancy
Inhaled insulin therapy in diabetes mellitus
Management of blood glucose 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 blood glucose in adults with 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
- Diabetes Control and Complications Trial Research Group, Nathan DM, Genuth S, et al. The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulin-dependent diabetes mellitus. N Engl J Med 1993; 329:977.
- Fleming DR, Jacober SJ, Vandenberg MA, et al. The safety of injecting insulin through clothing. Diabetes Care 1997; 20:244.
All topics are updated as new information becomes available. Our peer review process typically takes one to six weeks depending on the issue.