03 January 2007
There are many insulin available in Malaysia, including human insulin that is genetically engineered. Insulins are extremely pure with human insulin being the purest, and purified pork a close second.
But even the beef and beef-pork insulins are far purer than they were just 10 years ago. A few facts may help you work with your doctor to decide which insulin is best for you.
There are three characteristics of insulin. They are:
Onset. The length of time before insulin reaches the bloodstream and begins lowering blood glucose.
Peak time. The time during which insulin is at its maximum strength in terms of lowering blood glucose levels.
Duration. How long the insulin continues to lower blood glucose.
Here is a brief look at the kinds of insulin available. Remember, though, each person has his or her unique response to insulin, so the times mentioned here are only approximate.
Regular or short-acting insulin, referred to with a capital "R," usually reaches the bloodstream within 30 minutes after injection. It peaks anywhere from 1 to 3 hours after injection, and remains in the bloodstream for approximately 5 to 7 hours.
Intermediate-acting insulin generally reaches the bloodstream from about 2 to 4 hours after it is injected. It peaks 4 to 14 hours later, and stays in the blood for about 18 to 24 hours. The varieties of intermediate-acting insulin include both NPH and Lente. These are often used in combination with short-acting insulin. (Human Ultralente, which is considered to be a long-acting insulin, is absorbed at different rates in different people. Therefore, for some people, human Ultralente functions as an intermediate-acting insulin, while in others, its actions are long-acting.)
Long-acting insulins have a minimal peak activity, 14 to 24 hours after they are injected, and stay in the blood 20 to 36 hours. When using long-acting insulin, it is usually advisable to combine it with a short-acting insulin. This provides proper peaking of insulin effect at mealtimes. Long-acting insulins have a duration of about 24 hours and provide a nearly continuous insulin release.
Pre-mixed insulins are a convenience for those who draw up a mixture of NPH and Regular in one syringe. The most typical mixture is 70 percent NPH and 30 percent Regular. Pre-mixed insulin can be helpful for those, like the elderly, who have trouble drawing up insulin out of two different bottles and reading the correct directions and dosages. It's also useful for those who have poor eyesight or dexterity and is a convenience for people whose diabetes has been stabilized on this combination.
All insulins come dissolved in liquids, but the solutions have different strengths. The most commonly used strength in Malaysia today is U-100. That means it has 100 units of insulin per millilitre of fluid.
Not used in this country, but still used in Europe and Latin America, is U-40, which has 40 units of insulin per millilitre of liquid.
As you may know, different insulin strengths call for different syringes. For example, U-40 syringes are used with U-40 insulin and U-100 syringes with U-100 insulin, etc.
If you draw up your U-100 insulin in a U-40 syringe, you'll get two and one-half times the amount of insulin you need. While this mismatching isn't too likely to occur when you buy all your products in Malaysia, it is something to watch for when you are traveling in other countries.
For years, the most commonly used insulins were made from pork, beef, and beef-pork combinations. Today, recombinant DNA human insulins are the most widely used insulins in this country.
These insulins are made through genetic engineering. The genetic material is taken from either E. coli or yeast. The source of an insulin is important because it usually affects the speed of absorption, peak, and duration.
Human insulins are absorbed more quickly than other forms. Another important point is that insulins from animal sources are more likely to cause allergic reactions. However, many people have taken these insulins for years without problems.
Often people will be instructed to take a given amount of Regular and a given amount of another type of insulin, say NPH.
While it is acceptable to mix Regular insulin with NPH in the same syringe, this is not the case for Lente or Ultralente formulations (except for people who are already adequately controlled on such a mixture).
With these insulins, the Regular blends with the longer-acting insulin, leading to unpredictable results. NPH insulins do allow mixing, and if need be, syringes may be filled several days in advance. Often, however, it is easier to use a pre-mixed insulin.
These options should be discussed with your doctor. Additives. All insulins have added ingredients. These prevent bacteria from growing and help maintain a neutral balance between acids and bases. In addition, intermediate and long acting insulins also contain ingredients that prolong their actions.
These may vary among different brands of the same kind of insulin and can cause slight differences in the onset and duration of the insulin's action. In some rare cases, the additives can bring on an allergic reaction.
It does pay to shop around for your insulin. Prices can vary by several dollars a bottle depending on where they're sold.
In selecting a pharmacy for purchasing your insulin and diabetes supplies, consider one that is close to you and open during the hours you want to shop.
Look for a pharmacy that delivers. This can be helpful when you are ill or busy.
Use a store where a pharmacist is available, and get to know him or her. Make sure the pharmacist will take an interest in your medical needs, be available to answer questions, and tell you what problems to watch for.
Don't just ask for "NPH insulin", look at the full brand name, strength, and kind. In fact, you might bring a used bottle to make sure you get the exact same thing again. Then, before you pay, check the insulin label to make sure you have the correct insulin.
Make sure you will be using all the insulin you are buying before its expiration date.
Inquire whether buying more than one bottle of insulin at a time would be cheaper than buying it by the bottle. Of course, keep the expiration date in mind.
On the rare occasion that insulin lots must be recalled, check to see if the control number on any of your bottles matches that of the recalled lot.
Storage and safety.
Although manufacturers recommend storing your insulin in the refrigerator, injecting cold insulin can sometimes make the injection more painful.
To counter that, some doctors recommend storing the bottle of insulin you are using at room temperature. Most doctors believe that insulin kept at room temperature will last a month or so.
Remember, though, if you buy more than one bottle at a time -- a possible money saver -- store the extra bottles in the refrigerator. Then, take out the bottle ahead of time so it is ready for your next injection. Don't store your insulin at extreme temperatures.
Never store insulin in the freezer or in direct sunlight. Those who order insulin by mail should consider the effect of shipping during hot summer months in the south or freezing winter months in the north.
Ask the distributor how the bottles will be kept cool and inspect the bottles carefully when they arrive. Consider purchasing insulin by mail only during the milder months.
Before you use any insulin, especially if you have had it awhile, check the expiration date. Don't use any insulin beyond its expiration date. And examine the bottle closely to make sure the insulin looks normal before you draw the insulin into the syringe.
If you use Regular, check for particles or discoloration of the insulin. If you use NPH or Lente, check for "frosting" or crystals in the insulin or on the inside of the bottle, or for clumping, which is evidenced by little "pieces" in the insulin.
If you find any of these in your insulin, return the unopened bottle to the pharmacy for exchange or refund.