Diabetes and Insulin

Diabetes & Insulin: The Basics

A Basic Guide to the 6 Types of Insulin

Insulin is a hormone naturally created by the pancreas that enables the body to process blood sugar and transform it into energy. In people with diabetes, the body is unable to do this properly for one of two reasons. In those with Type 1 diabetes, the pancreas no longer makes any insulin at all and, therefore, the body in unable to process blood sugar. In those with Type 2 diabetes, the pancreas produces insulin, however, the body does not respond to it effectively, thereby hindering the ability to process blood sugar.

Do all diabetics require insulin treatments?

Since the body does not produce any insulin in those with Type 1 diabetes, everyone with this condition will require insulin treatments for the rest of their lives. Those with Type 2 diabetes do produce some insulin, the body just has a hard time effectively using it. Not all Type 2 diabetics require insulin injections. Additionally, factors like maintaining a healthy weight; eating a diabetes healthy diet and staying physical active can all reduce the need for insulin in Type 2 diabetics.

Why can’t I just take a pill?

While there are many diabetes medications that can be taken orally, insulin is not one of them. This is because insulin taken orally would quickly be broken down during digestion just like the protein in food. In other words, insulin in a pill form is absolutely useless. It needs to be injected into the fatty tissue beneath the skin in order to enter the bloodstream and do its job of processing blood sugar. There is one non-injectable form of insulin on the market. It’s called “inhaled insulin”, which we’ll touch on in the next section. However, this new insulin breakthrough does not replace the need for injectable insulin.

The Six Types of Insulin

There are six overall categories of insulin available today. Each is defined by three primary characteristics.

Onset – the length of time it takes the insulin to reach the bloodstream and begin lowering blood sugar. 

Peak – the period of maximum strength when blood sugar is lowered most effectively.

Duration - how long the insulin stays in the bloodstream and continues to work.

Many people living with diabetes require more than one type of insulin to effectively treat their disease. If you’re living with diabetes, your physician will help you formulate an insulin dosage and treatment plan based on which type of diabetes you have, your overall health, diet, age and other factors.

  1. Rapid-Acting Insulin

Rapid-acting insulin begins to work about 15 minutes after it is injected and then  quickly leaves the body within 2-4 hours. This type of insulin is typically taken just before mealtime to keep blood sugar from spiking after eating. Rapid-acting insulin is often used in conjunction with a longer-acting insulin.

  1. Regular or Short-Acting Insulin

This type of insulin usually kicks in about 30 minutes after being administered. The treatment can last up to eight hours with insulin levels peaking anywhere between 2-3 hours following injection. This type of insulin is also commonly used to cover rises in blood sugar at mealtime but can be injected a good amount of time before eating due to the longer period of effectiveness.

  1. Intermediate-Acting Insulin

Intermediate-acting insulin is not as commonly prescribed as other types. It generally reaches the bloodstream 2-4 hours after it’s administered, and its effectiveness can last up to 18 hours. This can make it useful for those who require overnight insulin treatments.

  1. Long-Acting Insulin

This type of insulin is designed to provide all-day insulin coverage. The premise is pretty simple - one injection will help stabilize blood sugar for a 24-hour period. Even so, additional insulin types (rapid-acting or regular) may be required to supplement Long-Acting Insulin at various times of day, based on things like meals, activity levels and other factors.

  1. Ultra-Long-Acting Insulin

The primary difference between long-acting insulin and ultra-long-acting insulin is that the latter does not peak. In other words, there is no time during the treatment when insulin effectiveness is significantly higher than at other periods. Ultra-long-acting insulin lasts consistently for about 36 hours and, therefore, reduces the risk of hypoglycemia (low blood sugar).

  1. Inhaled Insulin

This new way to administer insulin is currently only offered by one manufacturer - Afrezza. The big advantages are speed and a very short lifecycle. Inhaled insulin starts working in 12-15 minutes but leaves the body within three hours. This can be helpful to control blood sugar at mealtime as inhaled insulin can be taken literally moments before eating. It does not, however, replace the need for longer-acting insulin. So, using inhaled insulin does not mean you will entirely avoid insulin injections.

Premixed Insulin

Many individuals living with diabetes require more than one form of insulin. Sometimes it can be tricky getting it right, particularly for those with poor vision or dexterity issues. In many instances, doctors will prescribe “premixed” insulin that combines a rapid- or short-acting insulin and an intermediate-acting insulin in one vial. Of course, the precise mixture depends on a person’s individual requirements, but premixed insulin effectively eliminates the need to draw from two separate vials. IMPORTANT: Unless directed by your diabetes physician NEVER combine or mix different insulin medications.

How Do I Use the Different Types of Insulin?

First and foremost, this depends on your specific diabetes condition and doctor recommendations. That being said, here are a few examples of common insulin treatment programs:

Long-Acting Injections Once or Twice Daily

This is a common program for those with Type 2 diabetes who also take oral medications to treat their condition. Often, one or two insulin injections each day, usually with a long-acting or intermediate-acting variety, is enough to maintain proper blood sugar control.

Basal-Bolus Method

This popular regimen mimics the way the body naturally works with insulin. In those without diabetes, the body produces basal insulin to help manage blood sugar throughout the day, while bolus insulin is released at mealtimes to counteract the associated rise in blood sugar. The Basal-Bolus Method effectively recreates this natural process. A long-acting or ultra-long-acting insulin is taken for daily management (basal), while a rapid-acting insulin is added at mealtimes (bolus). This insulin treatment method is common among both those with Type 1 and Type 2 diabetes.

Sliding Scale Method

The Sliding Scale Method is essentially administering insulin based on current blood sugar test results. In other words, your insulin dosage is based on an immediate glucose meter reading and therefore may vary throughout the day. Your diabetes physician will help you formulate a blood sugar testing schedule that works best with your lifestyle and diabetes condition.


How to administer insulin

There are three primary ways to administer insulin – syringe, pen needle and insulin pump. It’s important to remember that you should never mix or dilute insulin without specific instructions from your diabetes physician. Additionally, never use expired insulin.

Insulin Syringe – This is the tried-and-true method that requires you to draw insulin from a vial and inject it into the back of the arm, thigh or stomach as directed by your physician.

Pens & Pen Needles – Insulin pens simplify the injection process by arriving pre-filled with the right amount of insulin as prescribed by your doctor. Some pens are disposable, while others are reusable with pre-filled cartridges. Pen needles are sold separately and come in a variety of different lengths and widths.

Insulin Pumps – An insulin pump is a doctor-prescribed wearable device that provides a continuous dose of insulin throughout the day. It can deliver both a steady stream of insulin and a quick burst of rapid-acting insulin as need. Insulin is delivered from the pump using an “infusion set” made up of a plastic tube and a stainless steel needle called a cannula.


Insulin treatments are a necessity for many people with both Type 1 and Type 2 diabetes. As with most aspects of living with diabetes, the two keys are being consistent and following your doctor’s orders. Always stick to your doctor-prescribed blood sugar testing and insulin treatment schedule. Should you ever have any questions about insulin or experience adverse reactions to an insulin injection consult your physician right away. 


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