Insulin is a hormone produced by the pancreas, which helps regulate blood glucose levels. This hormone is vital for the transport and storage of glucose in cells and helps to use glucose as a source of energy for the body. Insulin acts as a key to allow glucose access to cells. If glucose can’t get into cells, it builds up in the blood.
The pancreas produces insulin in two different ways: A slow and continuous one that helps keep glucose levels always stable between 70-100 mg / dl known as basal secretion. The other, fast and in greater quantity, secreted generally when the blood glucose has high values after meals; this is known as pulsatile secretion.
In the past, patients with diabetes were treated with bovine (cow) and swine (pig) insulin.
Until a few years ago, mainly human insulin was used with a chemical structure identical to that produced by the human pancreas. Human insulin is produced using semisynthetic methods, modifying it enzymatically. For nearly 50 years the only insulin available was from cows and pigs, until NovoNordisk discovered how to make synthetic human insulin using the key ingredient in a loaf of bread, yeast. Human insulin is obtained by genetic engineering to add the gene for insulin production to its DNA, in simpler terms, it has been genetically modified to produce insulin with a chemical structure indistinguishable to that produced by the pancreas beta cells.
Currently, insulin analogues, (i.e., chemical compounds that have similar properties to original human insulin), obtained by genetic engineering are mainly used, incorporating human genes for insulin production in yeast cells (insulin aspart) or bacteria, such as Escherichia coli (this happens with lispro and glulisine insulins). In this way, yeast or bacteria cells are tricked into producing insulin instead of their own proteins.
There are many different types of insulin, such as:
- Fast-acting and ultra-fast-acting insulins are pure insulins, without any additives.
- Intermediate-acting, which have additives such as protamine (salmon protein) or zinc to slow down their action.
- Long-acting insulins, whose solutions have a longer effect, acting by precipitation after injection (glargine) or by binding to proteins such as albumin in the blood (detemir insulin). These achieve the effect of pancreatic basal secretion.
To know how a type of insulin works, it is important to understand a drugs action profile. All insulin types have an onset of effect, which is the period from the injection of it until it begins to work. A maximum effect or peak of action, which is the period where there is more insulin effect, this must coincide with the maximum concentration of carbohydrates in the body, and an end of effect, which is the residual active insulin after the end of the peak of action.
Here is comparison table between the different insulin types:
|Rapid Action Insulin analogue||Ultra-fast acting insulin analogue||Intermediate acting insulin analogue (NPH)||Mix of insulin analogues||Long lasting insulin analogues.|
|General characteristics||Transparent||Transparent. they do not have any type of additive or retardant.||They are opaque. They use Zinc or protamine as a retardant.||They are mixtures of fast and intermediate analogues. Commercially prepared.||Transparent. Glargine insulin is a clear solution but it precipitates (becomes opaque) after injection due to the subcutaneous tissue higher PH. Detemir insulin binds to a protein in the blood, called albumin.|
|Beginning of action||Action begins ar ½ hour||10-20 minutes after injection.||1-2 hours||30min -1hour after injection.||Between 60-90 minutes.|
|Maximum effect||1-3 hours post injection.||1-2 hours post injection.||4-6 hours.||2-3 hours post injection.||Regarding Glargine insulin; It does not have a peak of action, although we can observe a maximum effect around 12 hours after its administration.|
|Duration effect||6 to 8 hours.||3-5 hours.||Between 10-12 hours||6-10hs.||Lasts between 17-24 hours depending on the insulin type.|
|When to inject it||30 minutes before meals.||10 minutes before meals.||30 minutes before meals. It is used as basal insulin when injected twice a day or in a single dose before bed in a multiple dose regimen.||10 minutes before meals.||Inject it at a fixed time every day.|
|Brands||–Apidra (insulin glulisine) –Fiasp (faster-acting insulin) –Humalog (insulin lispro)||–Humalog kwikpen –Novorapid flexpen –Apidra SoloStar -Apidra. Optiset,||-Insulatard Flexpen -Humalog Basal KwikPen||–Humalog Mix50 Kwikpen – Novomix 30 FlexPen -Novomix 50 FlexPen||-Lantus Solostar -Lantus Optiset –Levemir FlexPen -Levemir Innolet|
There is also a fast-acting inhaled insulin, whose onset of action is 10 to 15 minutes after inhalation and has a peak at 30 minutes. This insulin lasts approximately 3 hours. It is usually inhaled just before a meal and often used with long-acting injectable insulins.
On the other hand, in the market there are ultra-long-acting insulins whose effect starts at 6 hours, does not reach a peak and lasts 36 hours or more. It is used to provide insulin continuously for long periods of time.
How and when insulin is given is different for each person. This can change over time given the diabetes’s progression. Some may take just one type, others several different types of insulin throughout the day, depending on their lifestyle, eating habits, and blood sugar levels. The diabetes self-management education and support service (DSMES) is a useful tool in patient care.
Classification of insulin types according to diet-regimen:
Bolus insulin: It can be short-acting or rapid-acting. It is administered before or at the time of eating to control blood sugar levels.
Basal insulin: Intermediate-acting or long-acting. It is given to keep blood sugar levels stable between meals and throughout the night.
Basal-bolus regimen: Rapid-acting insulin given at mealtime, and long-acting insulin given once or twice a day.
Forms of delivering insulin
There are various forms of delivering insulin. The common are being syringes and pens, which deliver insulin through a needle. Pens are typically more convenient, and children typically find them more comfortable than syringes.
- Syringes: Have smaller capacity but are easier to use and more accurate.
- Pens: Some pens use cartridges that are inserted into them. Others are bought preloaded and thrown away after all the insulin has been used. The insulin dose is dialed into the pen and is injected through the needle. Cartridges and pens that are already loaded with insulin contain only one type of insulin. If two types of insulin are prescribed, two different pens will need to be used.
Advantages of syringes and pens
- Injections require less training than an insulin pump to be used and may cost less.
- Pens are easier to use than syringes, they are also portable and discreet.
- Pen needles are smaller and finer therefore, less pain.
Disadvantages of syringes and pens
- Both syringes and pens are less private than an insulin pump and not all types of insulin can be used with a pen. A syringe can mix two types of insulin, but with a pen you cannot do the same.
- Pens are more expensive than syringes and may not be covered by insurance.
- If insulin is injected close to the same place each time, fat deposits may form. Both problems can be unsightly and cause insulin to not do its job as well.
An insulin pump is a small device that releases insulin through a small plastic tube (catheter). The device continuously pumps insulin day and night. It can also release insulin faster (bolus) before meals.
There are two types of insulin pumps; traditional and patch pumps:
Traditional pumps include an insulin reservoir (cartridge) and a catheter. The catheter is inserted with a plastic needle just under the skin into the fatty tissue. This is held in place with an adhesive band. The catheter is connected by tubes to a pump that has a digital screen. This allows the user to program the device to deliver the necessary insulin. On the other hand, patch pumps are worn directly on the body with the reservoir and tubing inside a small box. A separate wireless device programs the release of insulin from the pump.
- You can program several basal infusions. This allows better adjustment to the different insulin needs that the person has during the day.
- It also allows better coverage of the “dawn phenomenon” that occurs when there are blood sugar increments in the early mornings, with this the basal rate of insulin in those hours can be increased.
- The continuous supply of insulin by the pump allows greater freedom of schedules. Thus, a meal can be delayed without fear that the effect of the administered insulin will end, as occurs in therapy with multiple insulin injections.
- The pump only uses fast-acting analogs, which ensures a more predictable effect, compared to slow-acting or intermediate-acting insulins.
- It allows modification of the basal rate of up to 0.025 U/h, and changes in boluses from 0.05 to 0.05 U too.
- It allows better adjustment of the insulin amount before exercise.
- Generally, the risk of severe hypoglycemia is reduced.
- In different studies it has shown an improvement in the child and their family’s quality of life. This improvement is fundamentally due to the time flexibility it offers.
- During pump therapy the insulin reservoir is very small. For this reason, it is more susceptible to complications such as, in the event of an interruption in insulin supply, ketoacidosis with hyperglycemia (high blood sugar). Usually with good education from the diabetes health team, patients on insulin pumps know how to avoid this situation.
- The pump must be worn 24 hours a day, which for some people means greater fatigue when controlling their diabetes.
- When on a pump, more frequent and regular monitoring is needed.
- It involves greater expense than therapy with multiple doses of insulin.
- Any child with diabetes, regardless of age, is a potential candidate for an insulin pump. In pediatrics, the main reason for recommending insulin pump therapy is to improve the life quality of the person with diabetes and their caregivers.
- This therapy is especially useful in those people who have a pronounced “dawn phenomenon” and especially in very young children. It is also especially indicated in those people with a history of recurrent severe hypoglycemia (low blood sugar) or inadvertent hypoglycemia.
How to store insulin:
It is recommended that insulin be stored in a refrigerator at approximately 36°F to 46°F. Freezing insulin must also be avoided.
Insulin can cause adverse drug effects that lead to emergency visits. From 2007 to 2011, nearly 100,000 estimated emergency department visits occurred each year in the U.S. for insulin-related low blood sugar or errors when taking insulin. Some of the most prevalent adverse reactions were:
- Nearly two-thirds of the patients had symptoms of severe hypoglycemia, such as shock, seizures, or loss of consciousness.
- Almost one-third of the emergency department visits resulted in hospitalization.
- Older adults are most vulnerable to insulin-related hypoglycemia leading to emergency room visits.
A call to the main physician should be made immediately if there are serious side effects. Calling 911 is a must if the symptoms are life-threatening. Serious insulin side effects and their symptoms can include the following:
- Severe low blood sugar. These symptoms include:
- Mood changes, such as irritability, impatience, anger, stubbornness, or sadness.
- Confusion, including delirium.
- Lightheadedness or dizziness.
- Blurred or impaired vision.
- Tingling or numbness in the lips or tongue area.
- Weakness or fatigue sensation.
- Nightmares or crying out during sleep.
- Serious allergic reaction. These symptoms include:
- A rash all over the body.
- Swelling of hands and feet.
- Hypokalemia, low potassium: with arrhythmia and muscle spasms.
Not only people with type 1 diabetes must inject insulin every day, often up to 4 or 5 times per day. Advanced type 2 diabetes patients may also need it too. Doctors and nurses are also educators who can teach the patient where and when to inject insulin and how to store it properly.
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