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If you were buying a car, you wouldn't dream of leaving the showroom without first asking the salesperson how safe it is, how well it drives, and how to operate it.

If you've been prescribed insulin -- a medicine used to treat diabetes -- you shouldn't consider leaving your doctor's office without asking how to take it, what side effects it might have, and how it will affect your diabetes.

Here is a list of important questions to ask your doctor before you start taking insulin: 

What type of insulin do I need?

Insulin comes in four basic forms:  

  • Rapid-acting insulin starts working within a few minutes after injection, but its effects only last for a couple of hours.
  • Regular- or short-acting insulin takes about 30 minutes to work fully and lasts for 3 to 6 hours.
  • Intermediate-acting insulin takes 2 to 4 hours to work fully, and its effects can last for up to 18 hours.
  • Long-acting insulin takes 6 to 10 hours to reach peak levels in the bloodstream, but it can keep working for an entire day.

Ask your doctor which of these insulin forms will work best with your diabetes type and blood sugar level.

Which insulin delivery method should I choose?

To inject insulin, you can use a syringe, pen, or pump. There is also a needle-free option called a jet injector. Discuss with your doctor the pros and cons of each method. Pens are easiest to use, pumps deliver insulin continuously, and syringes are the least expensive.

The decision may come down to cost, so find out which method your insurance will cover. If you don't have insurance or your plan won't pay for the type of insulin delivery method you prefer, ask your doctor about programs that can help you cover the cost.

How many times do I need to inject insulin each day?

People with type 1 diabetes may need up to three or four injections daily. Those with type 2 diabetes may need just one shot of insulin a day, possibly increasing to three or four injections.  

Find out how many times a day you'll need to inject, and how much insulin to inject in each dose. If you're using an insulin pump, ask your doctor when you'll need to give yourself an extra injection (bolus).

When should I take my insulin?

How often you take insulin depends on several factors, including:  

  • The type of insulin you use (fast-acting, premixed, etc.)
  • How much and what type of food you eat
  • How much exercise you get
  • Other health conditions you have
  • The type of insulin delivery system you use

Your doctor may want you to take insulin a half-hour before meals, so it's available when sugar from food enters your bloodstream. Find out exactly when during the day you need to take each of your injections, and what to do if you forget to give yourself an injection.

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