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Last updated on September 27th, 2022
Insulin is an essential hormone for metabolism in the human body. Its primary purpose is to move grape sugar (glucose) from the blood into the cells. There, the sugar molecules are needed to generate energy. Read this blog to learn about types of insulin with the help of a chart.
Understanding Insulin Production in the Pancreas
Insulin is produced in the pancreas, specifically in the beta cells of the islets of Langerhans. The name “insulin” comes from the Latin “insula,” meaning “island.” Beta cells first create proinsulin, which splits into insulin and C-peptide, both released in equal amounts. Measuring C-peptide levels in the blood helps determine insulin production.
Additionally, glucagon is produced in the alpha cells of the pancreas. It acts as an antagonist to insulin: while insulin lowers blood sugar, glucagon stimulates the release of stored sugar from the liver, raising blood sugar levels.
Working of Insulin in The Human Body
Summary
The small intestine breaks down carbohydrates into glucose, which passes through the intestinal wall into the blood and is distributed to body cells to generate energy.
According to the National Institutes of Health, insulin acts as a key, binding to insulin receptors on cell surfaces to allow glucose entry. In type 2 diabetes, this mechanism is disrupted, causing sugar to remain in the blood and raising blood sugar levels.
Insulin transports sugar into the cells of muscles, liver, kidneys, and fatty tissue but not the brain.
The brain cells can absorb glucose independently of insulin. The body also stores glucose, which it does not immediately need for energy production, in glycogen in the liver and especially in the muscles.
As per the NIH, in addition to its primary role, insulin also influences appetite in the brain and inhibits the breakdown of fatty tissue (lipolysis). When insulin is completely absent, the body uses adipose tissue for energy, leading to excess free fatty acids and potentially causing ketoacidosis, a serious metabolic imbalance primarily seen in type 1 diabetes and occasionally in long-term type 2 diabetes.
Human insulin resembles natural insulin, while analog insulins have different structures, resulting in varied onset and duration of action. There are various types of insulin, which will be discussed below.
Note: The following information on the onset, peak, and duration of insulin effects are general guidelines, as individual responses can vary significantly.
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Types of Insulin And How They Work
Insulin is crucial for blood sugar regulation, and understanding its different types helps individuals with diabetes manage their condition. Each type varies in onset, peak, and duration. Here, we’ll overview the various types of insulin and how they work.
1. Fast-acting Insulin
The Better Health Channel says that fast-acting or short-acting insulin lowers blood sugar levels during meals. Compared to human insulin, fast insulins like humulin R 500 have the advantage of making it easier to intercept increases in blood sugar after eating, and hypoglycemia due to prolonged action can be better avoided.
The blood sugar lowering effect usually occurs after around ten to 15 minutes and with particularly fast turbo insulin (even after five minutes). The most significant impact is often reached after approximately an hour before it subsides after around three hours. With human insulin, the peak is reached after two to three hours. The effects can last up to eight hours.
Fast-acting Insulin Working
Depending on the insulin preparation and the current blood sugar level, injecting fast insulin at a specific time before eating can be helpful. The planned meal should prevent the values from rising too much before the insulin effects. When it makes sense to keep a spray-eating interval and how long it should be, people with diabetes always clarify with their doctor as part of the therapy setting. Thanks to modern turbo insulins, eating or drinking between meals is often unnecessary.
Insulin for cartridges and pumps is usually available in a concentration of U100. U100 means that one milliliter of liquid contains 100 units of insulin.
Long-term and short-term insulins are also occasionally available. These come in pre-filled pens in the concentrations U200 and U300. Higher concentration:
- Extends the duration of action
- Reduces the volume of the injection.
2. Long-acting Insulins
Long-acting insulins, also known as basal insulins, meet the body’s basic insulin needs independent of meals. Typically injected once or twice daily, they mimic the pancreas’s natural activity by continuously releasing small amounts of insulin to stabilize blood sugar levels.
As stated by the NHS, these insulins vary in onset and duration (usually 30 minutes to 4 hours), lasting from 16 to 24 hours. Unlike other insulin types, they have a flatter action curve without a pronounced peak.
Intermediate or delayed insulins provide a middle ground between short and long-acting. For example, NPH (neutral protamine Hagedorn) is human insulin modified with protamine, resulting in a more noticeable peak. However, the risk of nocturnal hypoglycemia is higher with these than with long-acting insulins.
3. Mixed Insulins
Mixed insulins combine short-acting and long-acting insulin, available in various combinations (e.g., human insulin + NPH insulin) and mixing ratios, such as 30/70 (30% fast-acting and 70% long-acting). The short-acting component typically ranges from 15% to 50%, depending on the preparation. Mixed insulins, like NPH 70/30, are used in conventional therapy and are ideal for individuals with a regular daily routine, including fixed eating and exercise habits.
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Charts of Types of Insulin
1. Fast insulin analogs
In a solution, the insulin molecules stack together. They form what are known as hexamers. Hexamer is a group of six insulin molecules. These are dimers if there are two. One can also exchange individual amino acids in regular insulin. A person can, thus, achieve that these hexamers disintegrate more quickly.
That, too, in the subcutaneous adipose tissue after the injection. In insulin glulisine, the amino acid asparagine (in place B3) is replaced with lysine and lysine (in place B 29) with glutamic acid, in the case of insulin aspart.
As per the National Institutes of Health, IGlu is modified from human insulin by substituting lysine for asparagine at position B3 and replacing lysine at position B29 with glutamic acid.
It was possible to achieve faster monomer formation. This can be done by replacing the amino acid proline with aspartic acid instead of B 28. A quicker absorption into the bloodstream of the insulin molecules is also possible. This can be achieved via additives in the insulin formulation:
- EDTA / citric acid
- magnesium
- organic chaperones
- niacinamide.
Add niacinamide (vitamin B 3) to insulin aspart. This leads to faster absorption (faster aspart). Rapid insulin analogs control the postprandial sugar peaks. The duration of action is shorter than regular insulins. Thus, no snack is necessary.
Action profile of fast analog insulin: You can better adapt the insulin levels to the natural insulin secretion with short insulin analogs.
2. Basal insulins (delay insulins)
If you add zinc and neutral protein hawthorn (NPH insulin) to the liquid, the duration of action is longer. These insulins are cloudy because it is not a solution but a suspension. Therefore, you must swirl them (not shaken) at least 20 times to ensure that the insulin molecules are evenly distributed.
Effect profile of an NPH delay insulin (basal insulin):
3. Long-term analog insulins
Exchange the individual amino acids. In doing so, sticking the individual insulin molecules is possible in the subcutaneous fat tissue for a long time. Then, it breaks down into individual insulin molecules after a delay. Then, it can be absorbed into the bloodstream.
As per the Oxford Academic, insulin glargine, sold under the brand name Lantus® by Sanofi S/A, received its initial approval in the United States in 2000 (43). After the patent expired, similar insulins, so-called “biosimilars,” came onto the market from other companies. A longer duration of action is also possible. By attaching a fatty acid chain (Levemir/Degludec). These insulins bind to albumin in the blood. Their release occurs slowly back to the receptor by the albumin.
Effect Profile of Long-term Analog Insulin:
High Concentration of Insulins
Obesity continues to increase. Hence, higher and higher insulin doses are necessary to normalize blood sugar. This creates a problem with the amount of fluid injected into a site. The insulins like humulin R U 100 all had a 100 IU / ml concentration until recently.
Typically, no more than 40 units must be applied. That, too, subcutaneously to any one site. If higher doses were necessary, the patient had to inject twice. The insulin manufacturers have, therefore, developed insulins with a higher concentration.
4. Mixed Insulins
NPH insulins and long-acting insulin analogs are used in BOT (Basal Supported Oral Therapy). As published by the Wiley Online Library, a rapid-acting insulin analog is advised to be started at a dose of at least 4 units, or 50% of the two-hour post-meal blood glucose level (in mmol/L) for the meal that causes the highest glucose spike.
Individually defined HbA1c is not achieved with tablets or GLP-1 receptor agonists. Then, a BOT is done in the next step.
Administration of regular or fast-acting insulin analogs occurs with meals. Then, basal insulin with essential bolus therapy or ICT is given.
For selected, especially older patients, mixed insulins simplify therapy. Mixed insulins are a ready-made mixture of the following insulins:
- Human insulin
- Fast-acting insulin analog
- Basal insulin
The application occurs before breakfast and before dinner. Due to the basal insulin content in the mixture, there is also an insulin effect around lunchtime. Thus, the insulin needs of a smaller meal are covered.
Effect Profile of a Mixed Insulin
Conclusion
In conclusion, understanding the various types of insulin is crucial for effective diabetes management. Each type, from fast-acting to long-acting and mixed insulins, uniquely regulates blood sugar levels. By knowing how each insulin type works, individuals can make informed decisions about their treatment plans in consultation with healthcare professionals. With advancements like higher concentration insulins and tailored insulin therapies, managing diabetes has become more personalized, helping to stabilize blood sugar levels while reducing the risk of complications. Proper insulin use empowers individuals to live healthier lives with diabetes.
FAQ’s(Frequently Asked Questions)
A mix of regular and Neutral Protamine Hagedorn (NPH) insulin is known as premixed. Some common types of premixed insulin are Humulin M2, M3, and M5.
Soluble insulin is the short-acting type of insulin. It is also known as neutral and regular insulin. Some common soluble insulin brands are Humulin S, Velosulin, Hypurin neutral, etc.
ReliOn R is an intermediate-acting insulin. It starts acting within 2 – 4 hours of injection and is a safe, effective, and relatively low-cost option among various insulin brands in the market.
Humulin is a fast-acting form of insulin typically used for managing mealtime surges in blood sugar. On the other hand, Lantus is a long-acting insulin whose effect on the body is slow and steady for up to 24 hours post-injection.
Yes, they can be used interchangeably, as Novolin and Humulin are two different brands of insulin NPH.
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