Fast-acting insulin, also known as rapid-acting or mealtime insulin, is used by persons with both Type 1 and Type 2 diabetes, as well as some women with gestational diabetes. The purpose of fast-acting insulin is to reduce post-meal blood sugar spikes and to lower high blood sugar levels throughout the day.
A Faster Acting Insulin is Introduced in the Market
In 1996, a faster acting insulin named lispro (Humalog) was introduced in the market. This new insulin analog offered an advantage over regular insulin. Compared with regular insulin, insulin lispro has a more rapid absorption, onset, and shorter duration.
How does Insulin Work?
Insulin is a hormone released by the pancreas and secreted into the bloodstream to manage your blood glucose levels. Insulin ensures that when glucose is not used as energy, it is stored in the cells as glycogen until needed.
The goal of diabetes management is to keep blood glucose (sugar) levels as close to normal levels as possible. Normal blood sugar levels for someone with diabetes are as follows:
- Before a meal: 80-130 mg/dL
- About 2 hours after a meal starts: less than 180mg/dL
Let’s say, if you have not eaten for hours, your body still needs glucose. Your body releases the stored glucose from your liver into the bloodstream. Insulin and glucagon keep your blood glucose levels in range. When high glucose is detected, insulin is released and when blood glucose level drops (hypoglycemia), the pancreas releases another hormone, glucagon, whose major function is to release the stored glucose into the bloodstream. Refer to the graphic below.
When a person doesn’t have diabetes, the body releases insulin all day and overnight to keep blood glucose in a very narrow range. During meals, the body releases a burst of insulin to cover the food, especially carbohydrates that will be absorbed in the body and raise blood glucose levels. This process is done efficiently in persons without diabetes, resulting in fasting blood glucose of less than 100 mg/dl.
To manage fasting and post meal blood glucose levels, insulin therapy must imitate the natural body’s insulin secretion as much as possible. The pancreas releases insulin throughout the day. To mimic this, we use insulin called basal, and when you eat or drink, the body releases additional insulin. This is called prandial or bolus insulin.
When you have diabetes and need insulin, you may use a pump or injections. Your insulin therapy will attempt to replace your body’s basal/bolus insulin secretion. If you use a pump, you may have a basal and a bolus rate. You will use fast-acting insulin in your pump.
If you use injections, your insulin therapy schedule might look like this:
- Basal insulin: once or twice a day with a long-acting insulin
- Bolus (mealtime) insulin: several times a time with fast acting insulin before you eat. In addition, you may use bolus insulin to lo
Insulin Action Profiles
It is important to know how fast insulin starts to work, when it peaks, and how long it lasts in the body. This way, you can time when the ideal time is to administer an injection or bolus for the best glucose management.
For example, you want to match the time you start eating with the time the insulin starts working. If the insulin starts working and you have not started eating, you may experience low blood sugar (hypoglycemia).
These three terms to note in regards to how insulin acts::
- Onset – How quickly it begins to work in the body
- Peak – When the effect is most pronounced
- Duration – How long does it have a blood glucose lowering effect in the body
Let’s now look at the different types of fast acting types of insulins including their generic and brand names.
Fast Acting Insulin Names
There are several types of fast-acting insulins. The very rapid-acting insulins have an onset of less than five minutes. The rapid-acting insulins have an onset of five to twenty minutes, and the regular or short-acting insulin has an onset of 30 to 60 minutes. The table below lists the insulin names, brands, as well as their onset, peak, and duration. Click on the insulin name to see the onset, peak and duration.
How long does insulin last?
Insulin comes in vials, insulin pens, and in the case of Afrezza, which is an inhaled insulin, it is available in cartridges. These are some considerations to make sure you take care of your insulin appropriately:
- Insulin manufacturers recommend you keep your insulin in the refrigerator. Make sure you remove it from the refrigerator prior to using it. Injecting cold insulin may be painful.
- Once you open your insulin vial, discard it after 28 days.
- If you are using an insulin pen, read the pen insert for instructions. Most brands suggest 28 days.
- Afrezza inhaler must be replaced every 15 days from the day you start using it. Sealed blister cards and strips in use stored at room temperature must be used within 10 days. Opened strips stored at room temperature must be used in 3 days.
- Novolin R vial expires in 42 days.
- Keep insulin away from extreme heat or cold
Calculating Insulin Dosage
Bolus or prandial insulin (mealtime insulin) is administered before meals to reduce post-meals spikes. The amount of insulin is based on the following:
- Type of meal (quantity of food, type of food)
- Blood glucose value (what is the present blood glucose level)
- Physical activity (is the person planning to be active after the meal? Or was it active prior?)
- How much insulin is already on board (is there insulin from the previous dose?)
- Other medications
- Insulin to carbohydrate ratio (this is the person’s unique formula that calculates how many grams of carbohydrate will be covered by 1 unit of fast-acting insulin.)
Fast-acting insulins can also be used to lower blood glucose levels when there is hyperglycemia, or high blood sugar. If you have diabetes and your blood glucose is above 240mg/dl, you may be experiencing hyperglycemia.
Fast acting insulin is used to correct high blood glucose levels. Most persons with diabetes have been instructed to use a correction factor which is a math formula to help them calculate how many units of insulin they need to bring their blood glucose level to target level.
If you have diabetes and are unsure how and when to administer your insulin properly, please schedule an appointment with your doctor or diabetes educator.
Summary
Fast-acting insulins and even faster acting insulins are essential to manage your blood glucose if you have type 1 diabetes or if you have type 2 and need insulin therapy. There are many options for insulin therapies, and they could be delivered using syringes, pens, pumps or inhaled.
How Do I Eat AND Keep my Glucose in Check?
If you want to learn about how food fits and how to make adjustments to keep your blood glucose in range, check out my program On the Plate! Eating to Keep your Blood Glucose in Check
Do You Want To Learn More About Diabetes? Check Out These Articles!
Can Persons with Diabetes Eat Watermelon?
Is Almond Milk Good for Diabetes?
When to take Metformin, Before or After Meals?
Love Corn? Is Corn Good for Diabetes?
Is Beetroot Good for Diabetes?
Calculating Net Carbs What’s the difference between Carbs, Total Carbs, and Net Carbs?
