What is Insulin?
Insulin is an animal hormone with extensive effects on both metabolism and several other body systems (eg, vascular compliance). When present, it causes most of the body's cells to take up glucose from the blood (including liver, muscle, and fat tissue cells), storing it as glycogen in the liver and muscle, and stops use of fat as an energy source. When insulin is absent (or low), glucose is not taken up by most body cells absorbed and the body begins to use fat as an energy source. As its level is a central metabolic control mechanism, its status is also used as a signal to other body systems (such as amino acid uptake by body cells). Generally, it has several other anabolic effects throughout the body. When control of insulin levels fails, diabetes mellitus results.
Insulin is used medically to treat some forms of diabetes mellitus. Patients with type 1 diabetes mellitus depend on external insulin (most commonly injected subcutaneously) for their survival because of the absence of the hormone. Patients with type 2 diabetes mellitus have insulin resistance, relatively low insulin production, or both; some patients with type 2 diabetes may eventually require insulin when other medications become insufficient in controlling blood glucose levels.
Insulin is a peptide hormone composed of 51 amino acid residues and has a molecular weight of 5808 Da. It is produced in the Islets of Langerhans in the pancreas. The name comes from the Latin insula for "island".
Insulin's structure varies slightly between species of animal. Insulin from animal sources differs somewhat in 'strength' (i.e., in carbohydrate metabolism) in humans because of those variations. Porcine (pig) insulin is especially close to the human version.
Insulin Types and Insulin Comparison Chart
Insulin is a hormone made by the beta cells in the pancreas and used by the body so that glucose can enter the cells for energy. With Type 1 diabetes, the beta cells have been destroyed and are no longer active therefore patients with Type 1 diabetes use insulin injections. These insulin injections are used in place of the body's naturally produced insulin. With Type 2 diabetes, the pancreas is usually producing insulin however the body has developed a level of insulin resistance. This usually means that the insulin produced is not enough to keep the blood sugar levels balanced. Often a change in diet, an increase in exercise and oral medications are used first. When that is no longer effective, a person with Type 2 often requires injected insulin.
Insulin itself cannot be taken as a pill because it would be broken down during the digestive process. This digestion would prevent the insulin from arriving to the cells in your body in a state that will allow it to assist in turning glucose to energy. This is the reason insulin must be taken by needle injection into your blood stream under the fatty layer of the skin.
There are currently 20 different types of insulin sold in the US. Many factors, such as the species it was extracted from, injection site, and exercise level affect the onset, peak and duration of insulin. Generally speaking, each type of insulin has its own diffusion attributes.
There are five different generally accepted categories of insulin based on the following criteria:
- Onset - How soon it starts working.
- Peak time - When it works the hardest.
- Duration - How long it lasts in your body.
Indicated in the chart and descriptions below are generalizations of several different insulin. Every individual body may process and use the insulin differently. Always consult your physician before administering any medications.
Insulin Comparison Chart:
|Insulin Type||Begins Working||Peaks at||Ends Working in||Low Occurs at|
|Humalog||15-20 mins||30-90 mins||3-4 hours||2-4 hr|
|Novolog||15-20 mins||40-50 mins||3-4 hours||2-4 hr|
|Regular||30-60 mins||80-120 mins||4-6 hours||3-7 hr|
|NPH||2-4 hours||6-10 hours||14-16 hours||6-12 hr|
|Lente||3-4 hours||6-12 hours||16-18 hours||7-14 hr|
|Ultralente||4-6 hours||10-16 hours||18-20 hours||12-24 hr|
|Lantus||2-3 hours||almost no peak||18-26 hours||4-24 hr|
Regular insulin (pork, beef, beef/pork, or human)
is fast acting and lasts a short time in the body. It is sometimes used before meals to control the post-meal rise in blood sugar, and to lower blood sugar quickly when an immediate correction is needed. You must consult your physician before using any type of insulin.
Semi-Lente insulin (beef/pork)
has a short duration, but twice as long as Regular insulin. It is sometimes used to control post-meal rises in blood sugar and may be combined with Lente insulin. You must consult your physician before using any type of insulin.
NPH insulin (beef, pork, beef/pork or human)
contains added protamine for an intermediate-acting effect. NPH insulin provides a basal amount of insulin. Two injections a day are usually prescribed. You must consult your physician before using any type of insulin.
Lente insulin (beef, pork, or human)
contains added zinc, which gives it an intermediate-acting effect similar to NPH. Lente insulin also provides a basal amount of insulin. Two injections a day are usually prescribed. You must consult your physician before using any type of insulin.
Ultralente insulin (beef or human)
contains a lot of added zinc to give it the longest-acting effect. Note that Humulin Ultralente has a shorter peak and duration than beef Ultralente. Ultralente insulin provides the steadiest basal amount of insulin. One injection a day is used in combination with Regular insulin before meals. You must consult your physician before using any type of insulin.
Insulin Lispro, sold under the trade name Humalog
Humalog is a new man-made insulin that is very similar to naturally occurring human insulin. It has a more rapid onset and a shorter duration of action than human regular insulin. It is meant to be taken within 15 minutes of eating a meal and in combination with longer-acting insulin. The Diabetes Monitor has made additional information about Insulin Lispro available online. The University of Massachusetts Diabetes Clinics have found this new insulin to be helpful for many persons who need to take a short-acting insulin before meals but who have difficulty with meal schedules or with after-meal insulin reactions. You must consult your physician before using any type of insulin.
70/30 Insulin (human)
is a mix of 70% NPH and 30% Regular insulin. Two injections a day are usually recommended. You must consult your physician before using any type of insulin.
Insulin storage tips:
- Insulin will keep for 1 month at room temperature if kept cooler than 86 degrees and out of direct sunlight or heat.
- Unopened bottles of insulin should be stored in a refrigerator; but do not freeze insulin.
- Syringes may be pre-filled and stored in a refrigerator for up to 3 weeks. Be sure to roll the syringes before use to mix the insulin.
**All of the information above is strictly for referral and educational purposes only. All people with diabetes should consult their physician before using any medications to treat and manage their diabetes.