Lee Chung Horn
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  DIABETES MELLITUS

 

WHAT IS INSULIN? 

Inside the pancreas, beta cells make the hormone insulin. With each meal, beta cells release insulin to help the body use or store the glucose it gets from food.

In people with type 1 diabetes, the pancreas no longer makes insulin. The beta cells have been destroyed. They need insulin shots or injections to use glucose from meals.

People with type 2 diabetes make insulin, but their bodies don't respond well to it. Some people with type 2 diabetes need diabetes pills or insulin shots to help their bodies use glucose for energy.

Insulin cannot be taken as a pill. It would be broken down during digestion just like the protein in food. Insulin must be injected into the fat under your skin for it to get into your blood.

There are more than 10 types of insulin sold in Singapore. These insulins differ in how they are made, how they work in the body, and price. Insulin is made in labs to be identical to human insulin.

There are four main types of insulin, based on

  how soon the insulin starts working (onset)

when it works the hardest (peak time)

how long it lasts in your body (duration)

However, each person responds to insulin in his or her own way. That is why onset, peak time, and duration are given as ranges. 

Rapid-acting insulin (Lispro or Humalog) reaches the blood within 10 to 15 minutes after injection. It peaks 30 to 90 minutes later and may last as long as 5 hours. 

Short-acting (regular) insulin eg. Actrapid usually reaches the blood within 30 minutes after injection. It peaks 2 to 4 hours later and stays in the blood for about 4 to 8 hours.

Intermediate-acting (NPH and lente) insulins eg. Insulatard or Monotard reach the blood 2 to 6 hours after injection. They peak 4 to 14 hours later and stay in the blood for about 14 to 20 hours.

Long-acting (ultralente) insulin eg Ultratard takes 6 to 14 hours to start working. It has no peak or a very small peak 10 to 16 hours after injection. It stays in the blood between 20 and 24 hours.

Insulin glargine (Lantus) is a new long acting insulin with no peak. It is usually given once a day. Insulin detemir (Levemir) is another long-acting insulin analogue that does not have a distinct action peak.

Some insulins come mixed together eg Mixtard or Novomix or Humalog Mix 25. For example, you can buy regular and NPH insulins already mixed in one bottle. They make it easier to inject two kinds of insulin at the same time. However, you can't adjust the amount of one insulin without also changing how much you get of the other insulin. The proportions are fixed and cannot be altered.

Additives. All insulins have added ingredients to keep them fresh and help them work better. Intermediate- and long-acting insulins also have ingredients to make them act longer. Today's insulins are very pure. Allergic reactions are very rare.

Storage and safety. Using cold insulin can make your shot more painful. You can keep the bottle of insulin you are currently using at room temperature or warm the bottle by gently rolling it between your hands before you fill the syringe. If you buy more than one bottle of insulin at a time, store the extra bottles in the refrigerator until you start to use them. Never store insulin at very cold (under 36 degrees Fahrenheit) or very hot (over 86 degrees Fahrenheit) temperatures. Extreme temperatures destroy insulin. Do not put your insulin in the freezer or in direct sunlight. Insulin may lose some potency if the bottle has been opened for more than 30 days. Look at the bottle closely to make sure the insulin looks normal. If you use regular, it should be perfectly clear--no floating pieces or color. If you use NPH or lente, it should be cloudy, with no floating pieces or crystals on the bottle. Do not use insulin past the expiration date. 

Insulin Therapy

With the help of your endocrinologist, you can find an insulin routine that will keep your blood sugar near normal, help you feel good, and fit your lifestyle.

People diagnosed with type 1 diabetes usually start with two injections of insulin per day of two different types of insulin. People with type 1 diabetes generally progress to three or four injections per day of insulin of different types. The types of insulin used depend on their blood sugar levels. Studies have shown that three or four injections a day give the best blood sugar control and can prevent or delay the eye, kidney, and nerve damage caused by diabetes.

Most people with type 2 diabetes may need a single injection of insulin in the evening (at supper or bedtime) along with diabetes pills. Sometimes diabetes pills stop working, and people with type 2 diabetes will start with two injections per day. They may progress to three injections per day.

Self-monitoring. Checking your blood sugar and looking over results can help you understand how exercise, an exciting event, or different foods affect your blood sugar level. You can use it to predict and avoid low or high blood sugar levels. You can also use this information to make decisions about your insulin dose, food, and activity. 

Site rotation. The place on your body where you inject insulin affects your blood sugar level. Insulin enters the blood at different speeds when injected at different sites. Insulin shots work best and fastest when given in the abdomen. Insulin arrives in the blood a little more slowly from the upper arms and even more slowly from the thighs and buttocks.

Injecting insulin in the same general area (for example, your abdomen) will give you the best results from your insulin. This is because the insulin will reach the blood with about the same speed with each shot. Don't inject in exactly the same place each time but move around the same area. Each meal-time injection of insulin should be given in the same general area for best results. For example, giving your before-breakfast injection in the abdomen and your before-supper injection in the leg each day give more similar blood sugar results. If you inject near the same place each time, hard lumps or extra fatty deposits may develop. Both of these problems are unsightly and make the insulin action less reliable. Ask your doctor if you aren't sure where to inject your insulin. 

Timing. Insulin shots are most effective when you take them so that insulin goes to work when glucose from your food starts to enter your blood. For example, regular insulin works best if you take it 20 to 30 minutes before you eat. 

Too much or not enough insulin?

High morning blood sugar levels before breakfast can be a puzzle. If you haven't eaten, why did your blood sugar level go up? There are two common reasons for high before-breakfast blood sugar levels. One relates to hormones that are released in the early part of sleep (called the Dawn Phenomenon). The other is from taking too little insulin in the evening. To see which one is the cause, set your alarm to self-monitor around 2 or 3 a.m. for several nights and discuss the results with your doctor.

Is insulin dangerous or bad for me?

Insulin is not bad for you. Your endocrinologist will have very good reasons for recommending it for you. It is never used frivolously. It is used for a good purpose. Instead of harming you, it will help you regain your health, and protect you from serious diabetes complications (like blindness and kidney failure) that arise from poor glucose readings. Patients are also sometimes fearful that prolonged use is bad. This is also absolutely not true. Children with type 1 diabetes have no choice but to use insulin. They grow up and live to their 70s and 80s. They use insulin for 50 to 60 years, and remain well. Without insulin, they would not even live. Do not worry. Use insulin properly and with care, and it will serve you well.


 

Copyright of Lee Chung Horn Diabetes & Endocrinology 2009