what is insulin

Discovering that your blood sugar, or glucose, is high can be scary, especially because it’s a sign you may have prediabetes or diabetes.

Insulin is a hormone that plays a major role in regulating blood glucose levels.

“Normally, your pancreas produces insulin, which helps move glucose out of your blood and into your cells. Insulin also stops your liver from producing more sugar,” says Smriti Manandhar, MD, an endocrinologist at UPMC Western Maryland. “Insulin attaches to receptors on these cells, allowing glucose to enter them. Much like fuel powers a car, glucose gives your body the energy it needs to function.”

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Types of Diabetes

There are two distinct types of diabetes: type 1 and type 2.

Type 1 diabetes

In type 1 diabetes, the pancreas does not produce insulin. Sugar is unable to get into the cells, so the sugar level in the blood increases.

“When the blood sugar level rises above normal, it results in high blood glucose, called hyperglycemia,” Dr. Manandhar says. “Children and young adults are most frequently diagnosed with type 1 diabetes.”

Currently, no one knows how to prevent type 1 diabetes.

Type 2 diabetes

In type 2 diabetes, the pancreas still produces insulin, but the body doesn’t use it properly.

“Higher levels of insulin are needed to make cells take up the sugar, and the body may not be able to produce enough insulin to meet this increased need,” Dr. Manandhar says.

Over time, untreated type 2 diabetes can result in damage to the eyes, kidneys, nerves, and heart. Type 2 diabetes can be prevented or delayed with healthy lifestyle changes, such as:

  • Losing weight.
  • Eating healthy food.
  • Being active.

You are more likely to develop type 2 diabetes if you are overweight, sedentary, have high blood pressure or high cholesterol, or have a family history of type 2 diabetes.

Symptoms of Diabetes

The symptoms of both type 1 and type 2 can include:

  • Frequent urination.
  • Increased thirst.
  • Blurry vision.
  • Cuts or sores that don’t heal.
  • Repeated infections.
  • Numbness in hands or feet.
  • Extreme tiredness.
  • Rapid weight loss.

With type 2 diabetes, you may experience only some of these symptoms or none at all —especially at the early phase of the disease.

Using Supplemental Insulin

Your doctor may recommend treating your diabetes with supplemental insulin to help keep your blood sugar in the right range. This can involve giving yourself shots of insulin on a regular basis.

“Fortunately, insulin shots typically cause minimal pain because the needles are short and thin and the shots are placed into fatty tissue below the skin,” Dr. Manandhar says.

To manage your diabetes, you should work with your doctor to determine your target blood glucose level. Dr. Manandhar recommends having a blood glucose level between 90 and 130 before a meal and less than 180 two hours post-meal, as per American Diabetes Association (ADA) guidelines.

The A1C test measures your average blood sugar levels over the past 3 months — important information that shows how well you’re managing your diabetes. The recommended A1C is less than 7%.

“Individual factors, such as unawareness of low blood sugar or other health conditions, may affect someone’s target glucose levels, so they may need a more personalized target that is higher or lower than usual,” Dr. Manandhar says. “It’s best to work with your doctor to find the right targets for you.”

Ways to Take Insulin

How and when to take insulin is unique to each person because insulin comes in different forms.

“I have some patients who take one long-acting insulin a day, and some take long- and short-acting insulin multiple times a day depending on their lifestyle, food intake, and target blood sugar levels,” Dr. Manandhar says.

The three most common forms of insulin are syringe, insulin pen, and insulin pump.


A syringe is a disposable shot needle. If you use a syringe, you will measure the insulin and give yourself the shot. It usually goes into your belly, thigh, upper arm, or upper buttocks. Your doctor will tell you how much insulin you need per dose. Smaller-capacity syringes are easy to use and more accurate to measure.

  • If your largest dose is close to the syringe’s maximum capacity, buy the next size up in case your dosage changes.
  • If you need doses in half units, choose a syringe with half-unit markings.

Insulin pen

Insulin pens also deliver insulin through a needle. Some pens use cartridges that you insert into the pen. Others are prefilled and discarded after all the insulin is used. The insulin dose is dialed on the pen, and the insulin is injected through a needle.

Insulin pump

An insulin pump is about the size of a small cell phone. The pump delivers insulin through a thin plastic tube placed semi-permanently into the fatty layer under your skin, usually in the stomach area or back of the upper arm. It gives a basal dose of short- or rapid-acting insulin per hour.

“There are advantages and disadvantages to each insulin delivery method,” Dr. Manandhar says. “You may need to work with your doctor to find the right way or combination of ways to manage your diabetes.”

To learn more about diabetes, treatment, and prevention, talk to your doctor or visit the UPMC Centers for Diabetes Education and Support.

Editor's Note: This article was originally published on , and was last reviewed on .

About Endocrinology

The UPMC Department of Endocrinology stands as a national leader in research of diabetes and endocrine conditions. We partner with the University of Pittsburgh Division of Endocrinology and Metabolism for research and clinical trials. We treat diabetes, obesity, osteoporosis, hormonal disorders, and thyroid disorders at several locations across our communities. We also have specialized Diabetes Centers to help you manage your disease. Find an expert near you.