Insulin
What It Does And How It Works

Insulin

Contents

• What Is Insulin And What Does It Do?
• How Does It Regulate Blood Glucose?
• Why Is Insulin Essential?
• Insulin Resistance
• Types Of Insulin

Insulin is a hormone produced by a cluster of cells inside the pancreas called the Islets of Langerhans. The main function of insulin is to regulate the level of sugar (glucose) in the blood.

A hormone is like a chemical messenger. It is made in one part of the body (in this case, the pancreas) and is secreted (usually) into the bloodstream. Blood transports hormones to different parts of the body where they carry out their work. Hormones instruct cells in the body what to do. In this case, insulin tells cells to open up so that they can absorb glucose (sugar) from the blood and use it as fuel for energy. If glucose could not enter the cell, our organs would have no fuel and would quickly fail to work.

Other Functions Of Insulin
In addition to promoting the access of glucose into cells, insulin is also called a builder hormone. This is because it helps fat and muscle to form. It promotes the storage of glucose in the form of glycogen for times when glucose is not coming in. It also blocks the breakdown of protein.

How Does It Regulate Blood Glucose?

Blood glucose rises in the blood after eating a meal (particularly a meal which contains lots of carbohydrates) and falls when we have not eaten for a while or have exercised a lot (exercise uses up glucose). Typical signs of low blood sugar (hypoglycemia) are weakness and shaking (you may notice your hands shake if you go for long periods without eating). If your blood sugar is too high (hyperglycemia) glucose spills into your urine. This draws water out of your blood so you need to urinate more often and feel excessively thirsty. To avoid this situation, the body naturally tries to keep blood glucose levels steady at between 60 to 100 mg/dl (3.3 to 6.4 mmol/L). It does this by increasing the amount of insulin in circulation immediately after eating. It instructs cells to open up so that glucose can enter. Some of this glucose will be used immediately as energy by the cells, some will be converted into a storage form called glycogen for rapid use later, while some will be converted into body fat for eventual later use.

Why Is Insulin Essential?

Insulin is essential because without it, the body's cells cannot access glucose and use it for energy. Patients with type 1 diabetes produce little or no insulin because their pancreas has stopped producing it. If they did not receive daily shots of artificial insulin, they would quickly slip into a coma and die. Type 1 diabetics cannot take insulin in the form of pills. The type of insulin they need can only be injected with a syringe, insulin pump or insulin pen.

Insulin Resistance

Type 2 diabetics are slightly different. Either they have relatively low insulin production or - more commonly - they develop insulin resistance. A person with insulin resistance can have levels of insulin similar to healthy non-diabetics - but the insulin they produce is not particularly good at its job. The cells of the body are 'resistant' to instructions from the insulin, so they do not properly absorb glucose circulating in the blood. This leads to elevated blood sugar which requires insulin pills (usually) or insulin shots (less commonly) to correct. Insulin resistance is linked to prediabetes and Metabolic Syndrome. If not corrected it can cause longterm diabetes complications such as kidney disease, diabetes foot problems or eye disease.

Bottom line: If you have type 1 diabetes, you cannot live without insulin shots. If you have type 2 you might not need insulin pills straight away, but you may need to take them eventually if lifestyle improvements (like losing weight or a better diet) do not improve symptoms. However, if your diabetes symptoms worsen, you may need to progress to insulin shots.

Types Of Insulin

Rapid Acting Lispro Insulin
Lispro insulin, also called humalog insulin (by Eli Lilly) is a rapid acting type of insulin. It starts to lower glucose levels within 5 minutes of taking it, peaking within an hour and is no longer active after 3 hours. The main benefit is that you are freed from having to take a shot just after eating. Previously diabetics needed to take a shot within 30 minutes of eating or risk hyperglycemia. Novolog (insulin aspart) is another similar rapid acting insulin.

Short Acting Regular Insulin
This takes 30 minutes to start lowering glucose and peaks after 3 hours and is gone by 6 to 8 hours. Until rapid acting insulin was invented, short acting insulin was used by patients, before eating to keep their glucose levels consistent until their next meal.

Intermediate Acting
NPH and lente insulins are both intermediate acting types of insulin that take 2 hours to kick in and act for 10 to 12 hours. The purpose is to keep insulin levels smooth and controlled for half the day. It means there is always some insulin in the body - this way it closely imitates the way insulin should work in the body.

Long Acting Ultralente Insulin
Ultralente insulin takes 6 hours to become active and remains active for up to 26 hours. Originally it was meant to even levels of insulin requiring only one shot a day. However people can react differently to it, for many it only provides intermediate acting benefits.

Long Acting Insulin Detemir And Glargine
Insulin glargine or Lantus is a long acting type of insulin sold by Aventis. It becomes active within 1 to 2 hours of an injection and lasts for 24 hours. It provides smooth glucose control over the entire day and can be injected into any part of the body. As it provides predictable glucose control it tends not to cause hypoglycemia at night (which often happens with NPH insulin). Levemir (insulin detemir) produced by Novo Nordisk works similarly but for not quite as long.

Premixed Insulins
Diabetics who need to take more than one type of insulin may be prescribed premixed insulins. Several mixtures are available such as 70 percent NPH insulin and 30 percent regular; or 50 percent NPH and 50 percent regular; or 75 percent NPH-like insulin and 25 percent lispro insulin; or 70 percent NPH-like insulin and 30 percent insulin aspart. Premixed insulins are helpful for those who have problems mixing insulins in one syringe or who have poor eyesight.

Insulin Tips: Common To All Insulin

• Insulin can be kept at room temperature for 4 weeks or kept in a refrigerator until its expiry date. After which, it should be discarded.
• Insulin does not store well in excessive sun or cold, so protect it against these conditions.
• You can give an insulin shot through clothing.
• You can reuse disposable syringes a few times.

For more diabetes information, see the following:

• Endocrine system: Hormones, and how they work.
• Diabetes facts: Statistics, United States and worldwide.

Homepage: Womens Health Advice

WOMENS HEALTH ADVICE: ABOUT DIABETES
Sources
Please Note: Information provided on this site is no substitute for professional medical help. See Disclaimer.
Copyright. All rights reserved.