If you have been living with type 2 diabetes for a while, then you may be on a medication regimen that includes insulin. You’ve probably noticed that your type 2 diabetes is a bit different from other people’s. Every person’s body is different, and this is just one reason why the response to insulin treatments can vary from person to person.

Read on to ease your confusion about insulin and learn how it supports blood sugar management on the individual level.

How insulin works in the body

Insulin is produced naturally in the body by the pancreas. The pancreas contains millions of beta cells, and these cells are responsible for making insulin. Whenever you eat food with carbohydrates, your beta cells release insulin so that other cells in the body can use the blood glucose it gets from food for energy. In a sense, insulin acts as a key, letting glucose into the cells.

How insulin works without diabetes

Under normal circumstances, the body produces insulin after digestion. The presence of insulin triggers cells to take in the glucose and use it as energy. The ability of your cells to respond to insulin is called insulin sensitivity.

What happens to insulin when you have diabetes?

If you have type 2 diabetes, your body either can’t produce any or enough insulin, or is resistant to its presence. That means glucose is not able to get into your body’s cells effectively.

The inability for the cells to absorb the glucose in the blood causes elevated blood sugar levels. Blood sugar levels will be high after meals, and even between meals, since the liver makes glucose when we are between meals or sleeping. People who have type 2 diabetes often take diabetes pills or insulin shots to improve their blood sugar levels.

Characteristics of insulin

Insulin exists in suspension form. It comes in different strengths. The standard strength used in the United States is U-100. This means that it contains 100 units of insulin per milliliter of liquid.

While the strength of insulin varies, its action depends on three characteristics: onset, peak time, and duration.

Onset refers to the length of time it takes for the insulin to start lowering the blood sugar level. Peak time refers to the time when the insulin is at its maximum efficacy in lowering blood sugar levels. Lastly, duration refers to how long insulin continues to lower blood sugar levels for.

Types of insulin

Insulin is not available in pill form because your digestive enzymes can break it down. Insulin is, after all, a protein. Injecting it under the fat of the skin effectively transports it to the blood. There are several different types of insulin available for people who have diabetes:

  • Rapid-acting: This type of insulin starts to work 10 minutes after injection. Peak time is 30 minutes to three hours, but it continues to work for three to five hours. Examples of rapid-acting insulin include lispro (Humalog), aspart (Novolog), and glulisine (Apidra).
  • Regular-acting: Also called short-acting insulin, this begins to work 30 minutes after injection and its peak time is between two to four hours. It still continues to work for eight to 12 hours. Examples of short-acting insulin include Novolin R and Humulin R.
  • Intermediate-acting: This starts to take effect one to three hours after injection. It has a peak time of eight hours and is still effective for 12 to 24 hours. Examples of intermediate-acting insulin include Novolin N and Humulin N.
  • Long-acting: It begins working around four hours after injection and it has the ability to work for up to 24 hours. These insulins do not peak but are steady throughout the day. Examples of long-acting insulin including glargine (Lantus) and detemir (Levemir).
  • Inhaled insulin: A new type of insulin was introduced in 2015. It’s fast-acting and starts to work 12 to 15 minutes after inhalation. However, it only has a peak time of 30 minutes and is only effective for 180 minutes. Inhaled insulin like Afrezza should be taken in combination with long-acting insulin.

Factors that affect the absorption of insulin

Researchers have pointed out that the behavior of insulin after administration can vary. This means that there is a tendency for insulin not to follow the standard onset for it to start working. There are different factors that influence the absorption of insulin.

Site of injection

People with diabetes typically use three regions as the injection sites for their insulin: the upper arm, upper leg, and abdomen. Out of the three sites, the abdomen results in the most effective and rapid absorption of insulin. The upper leg region results in the slowest.

Concentration of insulin

The higher the insulin concentration, the more rapid the diffusion and rate of absorption. The most common insulin formulation is U-100, but U-500 and old U-40, which is no longer manufactured, are also available.

Thickness of the subcutaneous fat layer

Insulin should be injected into the fat layer just underneath the skin, where capillaries are abundant. People who are obese tend to have less blood flow in their fat tissue, which can cause a delay in insulin onset, peak, and duration following the injection.

Physical factors

Physical factors such as exercise, heat exposure, and local massage can speed up absorption of insulin by increasing the blood flow. For instance, exercise increases the blood flow and the cardiac output increases the heart rate. In one study published in the Journal of Pharmaceutical Sciences, doing fewer exercises increased the absorption of insulin by 12 percent.

How insulin works varies from one individual to another. Therefore, it is important to know what physical and lifestyle factors will affect how insulin acts in your body and how it works to lower your blood sugar level.