Insulin Therapy for Type 2 Diabetes

Editor’s Note: Some of the information in this article may be out of date. For a newer article on the same subject, please see “Type 2 Diabetes and Insulin: Getting Started.”

Al just couldn’t believe what he was hearing. “Insulin for me? But I exercise almost every day. I eat so much less than I used to, and I never skip my pills. What more can I do? Why has my diabetes gotten worse?”


Every number in Al’s blood glucose log is over 200 mg/dl and his glycosylated hemoglobin reading (or HbA1c, a measure of long-term blood glucose control) has slowly increased from 7.2% to over 10%. (The American Diabetes Association recommends aiming for an HbA1c less than 7%.) You can empathize with his frustration; he’s trying to do his part to keep his blood glucose within range, but his HbA1c keeps increasing. Why have his blood glucose readings gotten higher?

To understand the answer to this question, it helps to first understand why our bodies need insulin. Insulin is a hormone secreted by the beta cells of the pancreas that helps regulate the way the body uses one of its main sources of fuel, glucose. Its main job is to allow glucose in the blood to enter the cells of the body, where the glucose can be used for energy. Insulin also controls the rate at which glucose is produced and secreted by the liver. Glucose is stored in the liver in the form of glycogen. When a person’s blood glucose level drops, the liver converts glycogen to glucose and releases this glucose into the bloodstream. When there is enough glucose in the bloodstream, insulin secreted by the pancreas signals the liver to shut down glucose production. In people who do not have diabetes, the pancreas continually measures blood glucose levels and responds by secreting just the right amount of insulin—whether it is during the night, before meals, or during periods of stress. However, in people with Type 2 diabetes, there is a flaw in the system.

The two main problems behind Type 2 diabetes are insulin resistance and inadequate insulin secretion because of a defect in the beta cells. When a person has insulin resistance, the cells of his body are unable to take as much glucose from the bloodstream as they should, even when there’s a lot of insulin in the bloodstream. That is, the cells resist the insulin. On top of that, the liver may continue to secrete a lot of glucose into the bloodstream even when it isn’t needed. So insulin resistance can lead to higher blood glucose levels, especially following meals, and this causes the pancreas to secrete more insulin to compensate. At first, this may keep blood glucose levels within the normal range, but eventually the overworked beta cells produce less and less insulin.

So what happened to Al? His beta cells no longer secrete enough insulin for his needs. He could exercise like a professional athlete, follow a restricted diet, and follow every guideline for self-management, and his blood sugar levels would remain high simply because his pancreas cannot make enough insulin.

It’s not his fault…

Al is upset because he has tried hard to keep his blood glucose level within his target range, and he feels as though he has failed. But the truth is that Al didn’t fail; his pancreas did. In fact, his efforts at exercise and healthy eating probably created an environment that prolonged the life of his beta cells. Research confirms that the nature of Type 2 diabetes involves the progressive loss of beta-cell function. Taking the burden of producing lots of insulin off the beta cells by treating insulin resistance through weight loss, healthy eating, exercise, and certain medicines is clearly effective. In fact, the research devoted to the delay and prevention of Type 2 diabetes has shown the importance of preserving beta-cell function as well as reducing insulin resistance.

For years, people worried that one group of pills used to treat diabetes, the sulfonylureas, might be contributing to the decline of the beta cells. These pills, namely glyburide (DiaBeta, Glynase, Micronase), glipizide (Glucotrol, Glucotrol XL), and glimepiride (Amaryl), work by stimulating the pancreas to secrete more insulin. But research has proved that it is the beta-cell defect and progressive nature of Type 2 diabetes, not overstimulation by these pills, that leads to the decline in insulin production by the pancreas. Some people have a robust pancreas that continues to produce insulin when stimulated by these pills, and they never require injections of insulin. But if your pancreas no longer makes insulin, these pills will not help you.

There’s a lot you can do to control your diabetes. You can make healthy food choices, eat reasonable portions, exercise, lose weight, take your prescribed medicines, manage stress, and visit your health-care team regularly. In combination, these self-management practices can keep your blood glucose level (and blood pressure and cholesterol levels) within target range for a long time. But there are two things that you cannot control: your genes and the beta-cell defect of Type 2 diabetes. The need to make the transition to insulin therapy is not your fault.

Psychological insulin resistance

Insulin resistance is one of the metabolic hallmarks of Type 2 diabetes, but psychological insulin resistance is a horse of a different color. When faced with the need to take injections of insulin, many people resist. They plead, bargain, or never return to the health-care provider’s office. But much of this aversion is caused by fear over misperceptions, because insulin is a highly effective treatment, one that some diabetes experts would one day like to see started sooner rather than later.

Fear of needles. This is one of the most common reasons people avoid insulin therapy and one of the easiest to surmount. Syringe and pen needles are so small and fine that you barely feel them, but don’t take my word for it. Your diabetes educator or the nurse in your doctor’s office can show you the tiny needle and help you to do an injection on yourself. Most people are immediately relieved by the ease of injection and absence of discomfort.

If you can’t bring yourself to insert a needle in your skin, there are gadgets that will do it for you. These devices are designed so that you don’t have to see the needle. With the BD Inject-Ease Automatic Injector and Medicool InstaJect, you just press a button and the needle is inserted under your skin. The Owen Mumford Autoject 2 not only inserts the needle but injects the insulin as well. There are devices to hide needles too, such as the NeedleAid device, which can be used with a syringe or insulin pen, and the PenMate, which conceals the needle on the NovoPen 3. Jet injectors, including Medi-Jector Vision, AdvantaJet, GentleJet, Vitajet 3, and Injex 30, are needle-free. They force a stream of insulin through your skin with pressure, not a needle.

Having a negative experience or association with insulin. When some people are confronted with the need to inject insulin, they immediately think of someone they know who had a bad experience. One woman associated insulin with causing her aunt’s blindness, because soon after her aunt started insulin therapy, she lost her vision. In reality, years of untreated diabetes was responsible for her aunt’s loss of vision, not insulin. The most effective strategy for dealing with these negative experiences or associations is to share them with your health-care team. By learning what is worrying you, they can help you.

Feeling defeated. Some people report a sense of failure when they learn of their need for insulin therapy. They feel that they didn’t take care of themselves, often because of a few pieces of cake they “shouldn’t” have eaten or because of those times they were “too lazy” to exercise. Family members may reinforce these feelings because they don’t understand that Type 2 diabetes is progressive, and they blame the person with diabetes for self-neglect.

If you feel defeated, remember that perfection is not the goal of diabetes self-management. Even if you chose not to make healthy food choices or to exercise in the past, insulin therapy is not a punishment. But it can be an opportunity to reevaluate your choices and get involved in managing your health. Once you know the facts about Type 2 diabetes, you’ll see that you didn’t fail; your pancreas did.

Insulin therapy as threat. For years, your doctor threatened you with insulin therapy if you didn’t stop overeating. Unfortunately, this practice continues. Some well-intentioned health-care providers use insulin injections as a threat to motivate people. However, this only serves to send the message that insulin injections are something to be avoided, not that insulin is one of many effective treatments for diabetes. Health-care providers need to learn other methods for helping people who struggle with managing their diabetes.

Insulin inconvenience. It’s true; it is easier to take pills. However, newer insulin delivery devices minimize the inconvenience of taking injections, and insulin regimens can be tailored to your needs and your routines to make it easier.

Permanent or temporary?

In the treatment of Type 2 diabetes, insulin therapy may be prescribed for a variety of reasons and may be permanent or temporary. For example, some people require short-term, or temporary, insulin therapy when they take certain drugs such as steroids to treat other medical conditions. Because steroids such as prednisone can cause extremely elevated blood glucose levels, insulin may be used to lower blood glucose levels during steroid use. Generally, when the steroids are discontinued, the person no longer requires insulin therapy.

Infection or long periods of untreated diabetes may cause a condition called glucotoxicity. When someone is glucotoxic, elevated blood glucose levels interfere with the body’s ability to lower blood glucose. Short-term insulin therapy is used to lower blood glucose levels, eliminating the glucotoxicity and restoring the body’s normal glucose regulation.

Effective treatments for insulin resistance include weight loss, exercise, and insulin-sensitizing medicines such as pioglitazone (Actos), rosiglitazone (Avandia), and metformin (Glucophage). But some people may also require large doses of injected insulin, at least initially, to get past the barrier of insulin resistance and keep their blood glucose within range. Once these people have lost weight and begun exercising, they may be able to discontinue insulin therapy—as long as their pancreas continues to produce insulin. But people who have both insulin resistance and a pancreas that cannot secrete enough insulin require permanent insulin replacement.

Insulin replacement strategies

Just as there are different reasons to use insulin therapy, there are different formulations of insulin that are prescribed based on what your body needs. To get past the barrier of insulin resistance or to combat glucotoxicity, long-acting or intermediate-acting formulations of insulin may be prescribed. Long-acting insulins, which include Ultralente and the insulin analog glargine (Lantus), are typically injected at bedtime and are usually effective for up to 24 hours. Intermediate-acting insulins, which include NPH and Lente, are also often injected at bedtime but are effective for only 12 to 16 hours.

When both insulin resistance and inadequate secretion of insulin by the pancreas are the problem, two different insulin formulations are needed: one long-acting, or basal, insulin and one short-acting, or bolus, insulin. The long-acting insulin supplies the low-level, background insulin needed by the body at all times; the short-acting insulin supplies the insulin your body needs at mealtimes to handle the glucose from food. So-called “mealtime” insulins include Regular and the rapid-acting insulin analogs lispro (Humalog) and aspart (NovoLog).

Some people who need both long-acting and short-acting insulins use premixed insulins such as Humulin 50/50, Humulin 70/30, Novolin 70/30, Humalog Mix 75/25, or NovoLog Mix 70/30. A dose of 50 units of Humulin or Novolin 70/30 provides a combined basal, intermediate-acting insulin (NPH) dose of 35 units and a bolus, short-acting insulin (Regular) dose of 15 units. Other people mix their own long-acting and short-acting insulins or take each separately.

Practical concerns

If you are considering insulin therapy or if your health-care team is recommending insulin therapy, you’re probably wondering about the day-to-day mechanics of using insulin. Although this is not an exhaustive list, it may help you to get an overview of the subject.

Timing of injections. Taking your injections around the same time of day is important because insulin formulations release insulin into your system over a period of time, and although some basal insulins maintain a rather constant level of insulin in your bloodstream, other increase, peak, and decrease. If you inject your NPH insulin at 6 PM one night and 11 PM another night, you will see potentially wide variations in your blood glucose levels.

The rapid-acting insulins aspart and lispro can start to lower your blood glucose within five minutes of an injection, so they should be taken just before or after meals. If you wait too long to eat after injecting aspart or lispro, your blood glucose level could drop too low.

Mixing insulins. Insulin glargine (Lantus) cannot be mixed in the same syringe with any other insulin. All of the other insulins can be mixed together but if you mix Lente or Ultralente with any other insulin product, you must inject immediately after filling the syringe; if you don’t, the action profile—or the time it takes the insulin to start working, reach peak effectiveness, and taper off—will change.

Insulin delivery systems. Insulin is injected into a fatty part of the body so that the blood supply that feeds fat can absorb the insulin for use in the body. A syringe filled with insulin from a vial is the traditional method of delivering insulin. Pen-shaped devices called insulin pens, which are either prefilled with insulin or loaded with a cartridge of insulin, are also used. Devices prefilled with insulin called insulin dosers, which have a large display or dial for easier measurement of insulin doses, are also available.

The insulin delivery system that you choose to use can be based on your preferences, cost of the system and reimbursement, manual dexterity, visual acuity, and your unique lifestyle issues.

Storage. All insulin vials or pens not in use should be stored in the refrigerator. Most opened vials of insulin can be stored at room temperature for up to 28 days, after which they should be discarded. Prefilled insulin pens, insulin dosers, and insulin cartridges have very specific room temperature storage guidelines of 7, 10, 14, or 28 days depending on the type of insulin. Insulin stored beyond the room temperature storage guideline may be significantly less effective if used.

Checking blood glucose levels. There is no exact formula for deciding on an insulin dose, but one of the key factors used in regulating insulin doses is your blood glucose level. Blood glucose monitoring becomes an indispensable tool when you make the transition to insulin therapy. How often you need to check your blood glucose depends at least in part on the type of insulin prescribed. Plan to check more frequently when you first begin insulin therapy so that adjustments to your regimen can be made.

Side effects

The most common side effect of insulin therapy is hypoglycemia, or low blood sugar. Hypoglycemia is also a side effect of the sulfonylureas, the pills that stimulate the pancreas to secrete more insulin. Most episodes of hypoglycemia can be traced back to one of the following: taking too much insulin or oral medicine, skipping or delaying a meal, exercising strenuously without having a snack or carbohydrate drink, and drinking alcohol. Common signs and symptoms of hypoglycemia include sudden weakness, shaking, sweating, headache, hunger, palpitations, confusion, blurred vision, and irritability.

If you suspect you have hypoglycemia, check your blood glucose level with your meter to confirm it. To treat low blood sugar, eat or drink 15 grams of carbohydrate, wait 15 minutes for the carbohydrate to be absorbed, and check your blood glucose level again. If it has not increased in 15 minutes, eat or drink another 15 grams of carbohydrate and check again in 15 minutes. Some common foods containing 15 grams of carbohydrate include 4 ounces of orange juice, 6 ounces of ginger ale, 3 BD glucose tablets, 4 Dex4 tablets, and 6 saltine crackers.

Some people put up with frequent hypoglycemia because they can manage it well. But frequent hypoglycemia is a sign that something is wrong, and it can even be dangerous. When untreated or unrecognized, hypoglycemia can lead to seizures and loss of consciousness. Report episodes of hypoglycemia to your health-care provider.

Other than hypoglycemia, serious reactions to human insulin are rare. However, injecting insulin into the same spot over and over can cause the area to become thick and hard (a condition called lipohypertrophy) or pitted and dented (a condition called lipoatrophy). When tissues become damaged in these ways, insulin injected into these sites may not be absorbed consistently, causing your blood glucose levels to fluctuate. Lipohypertrophy and lipoatrophy can be avoided by changing the site of injection within an injection area such as the abdomen each time you inject. For each shot, pick a new site a finger’s width away from your last injection.

Frequently asked questions

People who are starting insulin therapy naturally have questions. I’ve listed and answered some of them below.

Does insulin make you gain weight?

In addition to allowing glucose in the blood to enter the cells of the body, insulin also helps the body store fat. If you don’t have enough insulin, you lose weight, and if you have too much insulin, you gain weight.

If you routinely take more insulin (or sulfonlyureas) than your body needs, you will gain weight. This could happen, say, if you kept your blood glucose in the 60–70 mg/dl range and endured frequent bouts of hypoglycemia. If your blood glucose levels fall too low frequently, contact your health-care provider and talk about lowering your insulin dose.

Some people view insulin therapy as a license to eat whatever they want because they can just take more insulin to keep their blood sugar level in range. If you frequently overeat and inject extra insulin, however, you will gain weight.

If your pancreas is not secreting enough insulin and your blood glucose is elevated, your cells will use fat for energy, and you will lose weight. Once insulin therapy is initiated and your body burns glucose instead of fat, you will gain the weight back. This is a positive sign that your body is working properly again.

What is an insulin pump?

Another option for delivery of insulin, an insulin pump is a beeper-size device that contains a cartridge filled with short-acting insulin or a rapid-acting insulin analog. The pump is connected to small, flexible tubing, and the tip of the tubing is inserted into the fatty tissue under the skin. The insulin pump releases small amounts of insulin into the body every few minutes. When food is eaten, the pump can deliver a larger quantity of insulin right away. With a pump, you get closer to receiving the right amount of insulin at the right time: large amounts when you eat and small amounts between meals. The rate of insulin delivery can also be adjusted for exercise, periods of stress or illness, and other activities or occurrences that might affect blood glucose level. Insulin pumps are used most commonly by people with Type 1 diabetes, but people with Type 2 diabetes who require insulin therapy can be candidates for insulin pump therapy. Even Medicare provides reimbursement to people who meet certain criteria.

What does it mean if I have to keep taking more insulin?

Taking more insulin does not mean that you are getting sicker. Health-care providers use a formula to decide your starting dose, but they always begin with a small dose because the formula only serves as a guideline. When beginning insulin therapy, you would expect to slowly increase the dose of insulin based on your blood glucose monitoring results. The dose of insulin that works for you depends on factors such as the amount of insulin your pancreas still makes, how resistant you are to insulin, your activity level, other medicines you take that raise blood glucose, and how much you eat.

You can make a smoother transition to insulin therapy when you have help. Seek the counsel of a certified diabetes educator with whom you can share your concerns and feelings about insulin therapy. Starting insulin is a big step, but the payoff—better blood glucose control—is worth the effort.