What Is Insulin?

In 2020, the Centers for Disease Control and Prevention released its National Diabetes Statistics Report, which describes the “state of the disease” in the United States. According to the report, 34.2 million Americans, or just over 1 in 10, have diabetes.


Diabetes is a chronic, potentially life-threatening condition in which the amount of sugar circulating in the blood stream is too high, the CDC reports. There are several different types of diabetes, with Type 2 being the most prevalent, accounting for 90% to 95% of all cases of diabetes.

Your risk of developing Type 2 diabetes increases if you have a family history of the disease. Other risk factors include:

— Age.

— Being overweight or having obesity.

— Not exercising enough.

— Not eating a healthy diet.

— Genetics.

— Certain ethnic groups, like African Americans, South Asians, American Indian and Latinos.

Also sometimes called non-insulin-dependent diabetes, Type 2 diabetes can often be controlled through diet, exercise and oral medication, the CDC notes. However, as it progresses, patients may need to start taking insulin to control blood sugar.

Type 1 diabetes, on the other hand, is an autoimmune condition that develops when the pancreas stops making insulin. Sometimes referred to as juvenile diabetes, this type of diabetes is typically diagnosed in childhood. The CDC reports that risk factors for this type of diabetes are less clear, but family history seems to play a part.

There are about 1.6 million people in America who have this form of diabetes, and they are dependent on insulin right from diagnosis.

[READ: What Are the Treatments for Type 2 Diabetes?]

What Is Insulin?

“Insulin is a natural hormone made by your body that regulates the amount of glucose, or sugar, in your bloodstream,” says Dr. Richard Seidman, chief medical officer of L.A. Care Health Plan, the largest publicly operated health plan in the country.

Insulin helps your body use sugar, or glucose, from carbohydrates in the foods you eat. “After we eat or drink, our blood sugar level starts to rise, and the beta cells in our pancreas are signaled to release insulin into our bloodstream,” says Ellie Kagan, a pediatric nurse practitioner and diabetes educator at Mt. Washington Pediatric Hospital in Baltimore.

“I often describe insulin as an Uber driver,” Kagan says. “Because the glucose can’t directly enter the cells, it needs a driver, or insulin, to take it there. When there are enough Uber drivers to deliver the glucose, the glucose levels (in your blood) naturally go down after a meal and the cells are fueled.”

Another way to think of insulin is like a key that unlocks glucose’s entrance into the cells of the body, says Dr. Natasha Akhter, an assistant professor of medicine at Duke University School of Medicine and an endocrinologist with the Duke Endocrinology Clinic in Durham, North Carolina.

Insulin also “helps store glucose in other parts of your body, such as your liver, fat and muscles, to be used later,” Seidman adds. It works by “signaling your other body parts to release, or uptake, glucose as needed by your body.”

And it’s important to use insulin if your doctor prescribes it because if your blood sugar is too high too often, that can lead to health consequences, Seidman says. “Patients with diabetes have too much glucose in their blood, which can cause problems with their eyes, kidneys, heart and other organs.” Foot problems are also a major concern for people with diabetes.

[READ: Living Well With Type 1 Diabetes.]

More than Just Glucose Control

In addition to helping regulate blood sugars, “insulin is an important hormone for your body’s metabolism,” Seidman says.

The body produces dozens of hormones, and insulin works in concert with many of them to regulate various aspects of health.

For example, if you have low thyroid hormone levels, that “may increase your risk of insulin resistance and lead to diabetes,” Seidman says. That’s because thyroid hormones and insulin work in partnership to help control body weight, temperature and other functions. If one is out of whack, it can create a whole range of additional health concerns and risk factors.

Types of Insulin

So, insulin, it turns out, is pretty important to the overall functioning of your whole body. When your pancreas can’t make any or enough of it, you’ll have to rely on other sources for it.

There are many different types of insulin available in the U.S. “They differ in how quickly they work, when they peak and how long their effects last,” Kagan says.

Types of insulin include:

Rapid-acting insulin, which acts within 15 to 30 minutes and lasts about three to four hours.

Short-acting (also called regular) insulin, which acts within 30 minutes to an hour and can last five to eight hours.

Intermediate-acting insulin (also called NPH), which works within 90 minutes to two hours and has a peak action in four hours.

Long-acting insulin, which works within an hour and may last 24 hours.

Ultra-long-acting insulin, which also works within an hour and may last up to 48 hours.

There also are versions that combine these different types. For example, your doctor may prescribe a combination of intermediate-acting and regular insulin or intermediate and rapid-acting insulin to meet your needs best.

“Most insulin is given as a subcutaneous injection,” Seidman says. This means you’ll use a small needle to inject the medication under the skin.

“It can’t be taken as a pill because it would be broken down during digestion, just like protein in food,” Kagan says. “It must be injected so that it works properly, just like the insulin produced in our bodies.”

However, “there are now new ways to get insulin into your body, like inhaled insulin,” Seidman says. This type might be best suited for people who have a fear of needles or otherwise can’t inject themselves. But people with asthma or chronic obstructive pulmonary disease likely can’t take this type of insulin. People with Type 1 diabetes who use inhaled insulin typically have to use long-acting insulin too.

Additionally, some people may use an insulin pump that delivers a stable, continuous dose of insulin or a surge dose around mealtime. This approach may be preferable to some patients, especially those who don’t like to take multiple injections a day.

To that concern, Evan Sisson, a certified diabetes educator and professor at the Virginia Commonwealth University School of Pharmacy in Richmond, notes that these days, the injection devices have become so small, they can be carried around like a pen and the needles are so tiny, you may not even feel it. “Sometimes patients are hesitant but once they try it, they say, ‘Is that all it is?'” Sisson says.

[SEE: Exercising Safely With Diabetes.]

Tailoring the Type and Dose of Insulin for You

You and your health professionals will work together to develop a plan that works for you. Factors your doctor will consider in determining the type and dose of insulin may include:

— Insulin onset, or when it lowers blood glucose.

— Peak time, or when it’s working at maximum strength.

— Duration, or how long it continues to lower blood sugar.

“We try to find out about a person’s life and what they eat to match their insulin to that,” Sisson says.

One important component of using insulin is getting the dose right. If you take too much insulin, you could develop low blood sugar, or hypoglycemia. “It can happen if a higher-than-necessary dose of insulin is taken after skipping a meal or sometimes when other oral hypoglycemic medications are used inappropriately,” Akhter says.

“The standard practice is to have patients with diabetes on once-a-day basal insulin, which can be long-acting or ultra-long-acting. Rapid-acting is usually added three times a day for mealtime,” Akhter says. The amount of rapid-acting insulin used may depend on your blood sugar and the number of carbs you eat during a meal.

However, insulin use for each diabetes patient will differ. For instance, if you have high blood sugar even after fasting, long-acting insulin would be beneficial. If your fasting blood sugar is normal but your blood sugar is elevated after meals, then rapid-acting insulin would be more appropriate, Kagan says. Insulin can also be combined with oral diabetes medications in some patients to optimize control.

Possible Side Effects of Insulin

Low blood sugar is the most common and serious side effect of insulin — and the risk is higher in those receiving continuous insulin therapy, Kagan says. That’s why you need to consult your doctor to get a better handle on using insulin if you are required to take it.

Another possible side effect is something called lipohypertrophy, or extra lumps of fat under the skin around a commonly used injection site. That can occur if you don’t rotate your injection site. “It may be unsightly, mildly painful and may change the timing and completeness of insulin action,” Kagan says.

It’s also possible to develop an infection at the injection site. Make sure to wash your hands with soap and water before you administer an insulin injection.

The Cost of Insulin

While insulin is certainly a wonder drug for millions of people with diabetes, it can be very expensive. That’s because “it’s a therapeutic biological product that takes much more to produce than oral medications,” Seidman says. “Instead of using simple chemical reactions in a lab to produce oral medications, biologic therapies are made from living organisms using complicated manufacturing processes.”

Unfortunately, this means “there are no generic medications with biologics because manufacturers cannot exactly replicate the same process as they do with generic oral medications.”

Historically, production of insulin was controlled by just a few drug manufacturers, which has also driven up costs and limited competition. “However, with the approval of biosimilars, with similar therapeutic efficacy, we hope to see these drug costs decrease in the future,” Seidman says.

He notes that in July 2021, the Food and Drug Administration approved the “first interchangeable biosimilar insulin,” a medication called Semglee. “Similar to generic medications where a pharmacist can automatically substitute a generic medication for a brand-name medication, a pharmacist may now substitute Semglee for Lantus,” a type of long-acting insulin.

“Prior to Semglee, pharmacists were not able to substitute any biological products,” Seidman explains. “Approval of Semglee is great news for patients and our health care system since it’s a lower-cost alternative for patients who need long-acting insulin to keep their blood sugar under control.”

Follow Your Prescriber’s Advice

No matter the type of insulin you use, remember that sticking with your insulin schedule is really important. Don’t stop taking your insulin, Seidman warns, as a condition called diabetic ketoacidosis can develop if you do. This condition causes “blurred vision and mental confusion that can lead to loss of consciousness and eventually death if left untreated.”

In all cases, if you’re having trouble affording your insulin, tell your health care provider. There may be workarounds or programs available to help you get the medication you need to survive.

More from U.S. News

Questions to Ask an Endocrinologist

What Are the Causes of Diabetes?

Top Vitamins for Men

What Is Insulin? originally appeared on usnews.com

Update 03/30/22: This story was published at an earlier date and has been updated with new information.

Related Categories:

Latest News

More from WTOP

Log in to your WTOP account for notifications and alerts customized for you.

Sign up