Understanding insulin therapy and its role in diabetes treatment can help you be more successful in managing the condition. Your first source of information is your doctor, but when you’re newly diagnosed, all the facts about insulin may seem overwhelming, and you might feel as though you have more questions than answers.

“That's common, so don’t be afraid to ask a lot of questions,” says Anthony L. McCall, MD, PhD, an endocrinologist and a professor of diabetes at the University of Virginia Health System in Charlottesville. Your doctor has the answers you need as well as experience with the emotions you might be feeling. Dr. McCall says that confusion, anxiety, and frustration are common when people with diabetes are first faced with the need for insulin therapy, but after concerns are addressed, most people find that administering an insulin injection is surprisingly easy.

To help you get a handle on your diabetes treatment plan, here are answers to frequently asked questions about insulin therapy. Use them as a starting point for further conversations with your doctor.

Why do I need insulin?

Insulin is a hormone that’s essential for controlling blood sugar and helping the body use blood sugar for fuel. If you have type 1 diabetes, you need to take insulin because your body isn’t making it on its own. If you have type 2 diabetes and need insulin, it’s because your body has stopped making enough insulin to meet its needs, which can happen over time. This is the result of two factors: “One is the failure of the body to respond appropriately to insulin, which is called insulin resistance, and the other is an inability of the pancreas to make enough insulin to overcome that,” says Mark E. Molitch, MD, an endocrinologist and a professor of endocrinology in the division of endocrinology, metabolism, and molecular medicine at Northwestern University's Feinberg School of Medicine in Chicago. There are also some situations in which you might need insulin for a short period of time, such as after heart surgery or a bout of pneumonia, when your body is working hard to recover and may not be handling insulin production as efficiently.

Will I need insulin for the rest of my life?

If you have type 1 diabetes, the answer is “yes,” although scientific research offers hope that one day pancreas tissue transplants could make it possible for your body to make insulin on its own. If you have type 2 diabetes, the answer is more complicated. Most people with type 2 diabetes will take insulin for the rest of their lives once it’s started, McCall says, but some people may be able to stop if they make a dedicated effort to lose weight and manage other lifestyle factors that caused them to need insulin therapy in the first place.

Do insulin injections hurt?

“Local discomfort from an injection is something most people are afraid of, but the delivery systems these days — with tiny needles you can’t see and much less pain on injection — make it easier for most people to do," McCall says. Depending on your insulin needs, you might want to consider an insulin pump that automatically delivers insulin whenever you need it via a catheter system.

Does insulin treatment cause weight gain?

“Some weight gain occurs with insulin treatment, mostly due to preventing the body from losing calories by excreting sugar in the urine," McCall says. "This can be minimized by using certain diabetes medications along with insulin, watching your diet, and staying active." Overall, he says, weight gain related to insulin can be minimal.

Does insulin treatment lead to complications, like blindness?

According to Dr. Molitch, many people with diabetes who are told they need to take insulin for type 2 diabetes vividly recall older relatives who started insulin and simultaneously experienced a severe complication, such as the need for amputation of a limb or blindness. Although these can be complications of uncontrolled diabetes — not diabetes treatment — your older relatives might not have been prescribed insulin until complications were already forming. These days, Molitch says, if you use insulin to maintain good blood sugar control, you can slow down the development of common diabetes complications.

Can I have a bad reaction to insulin?

People with diabetes rarely have an allergic reaction to insulin, McCall says. If that happens, you and your doctor will work with an allergy specialist to control your response. The most severe insulin reaction is hypoglycemia, or low blood sugar. “It’s not common in people with type 2 diabetes, but it can occur, and it’s important for you and your doctor to know how to use insulin to minimize the occurrence of hypoglycemia and promptly remedy it if it does happen,” McCall says. Your doctor will likely suggest that you carry sugar tablets or make sure you know when to drink a small amount of juice to correct low blood sugar. You should also wear a medical alert bracelet or necklace to let people around you know you have diabetes.

Will I become resistant to insulin?

By the time a person with type 2 diabetes needs insulin, he or she will probably know all about insulin resistance. “Higher doses of insulin are often used if people with type 2 diabetes are more sedentary or don’t reduce their calorie intake as they age, which both affect how well insulin works,” McCall says. "Insulin resistance is part of what goes wrong with type 2 diabetes, but healthy living can help." Maintain a healthy weight by watching your diet and staying active.

Can I fail at managing diabetes with insulin?

Some people look at the need for insulin as an indication of their efforts to manage diabetes. But Molitch says that type 2 diabetes is a progressive disease and that for some people, even with the best efforts, insulin will be necessary. He encourages thinking of it as a natural consequence of the condition rather than a failure on your part.

How will I know how much insulin to take?

Your doctor, a nurse, or a certified diabetes educator will work with you to determine how much insulin you need. Some people do well with one dose of insulin that lasts all day. Others need to take additional insulin before meals. Learning how to adjust insulin in response to your blood sugar levels and your lifestyle is part of managing diabetes. Regular blood sugar checks, such as before meals and before you drive, will help you stay in control and safe.

When do I need to call my doctor?

You should be seeing your doctor regularly, but if your blood sugar levels are running too high or too low, McCall says you should call your doctor immediately. That's a sign that you're not managing insulin well and need medical help. Though what's considered normal can vary from person to person, he says that levels over 200 or below 80 or 90 generally warrant a call. Also check in with your doctor any time you have questions about dosing.

Can I overdose on insulin?

Technically speaking, yes, but Molitch says that "it's really hard to overdose with insulin.” Although overdosing on insulin is rare, it’s a good idea to know the signs and how to respond. Taking too much insulin can cause hypoglycemia. Symptoms include hunger, dizziness, sweating, nervousness or anxiety, shakiness, sleepiness, and trouble focusing, as well as problems with speech or thinking. Most of the time, you can correct this quickly with a small amount of juice, a carbohydrate snack, or sugar tablets. However, at its worst, hypoglycemia can cause you to pass out or can be fatal. If your condition doesn’t resolve quickly after eating or you suspect an overdose, call your doctor immediately, get to an emergency room, or call 911.

For many people with diabetes, taking insulin is part of daily living — and you can live well on insulin. There are many insulin treatment options available to suit your lifestyle. The key is to work closely with your doctor and diabetes care team and to get comfortable asking questions about your insulin therapy.