Insulin Therapy 101 - Insulin Injection Basics

Insulin is a hormone produced by your pancreas whose primary function is to lower blood sugar. It does this by binding to insulin receptors on the cell wall which open glucose transporters. Once the glucose transporters are opened by the action of insulin, glucose can flow freely from the blood into the cell.

If you are insulin dependent your body relies on insulin injections in order to function correctly. This is either because your pancreas is not secreting any insulin, as in type 1 diabetes), or else the insulin that your pancreas is making is not doing its job properly, as in type 2 diabetes.

Insulin Basics

Before we jump into discussing the various insulin regimens, I need to first explain two terms which you will come across frequently:

Basal insulin - This is the injection of a long-acting insulin which mimics the insulin secretion of the pancreas. A single basal shot of insulin continues to act slowly throughout the day, therefore you only need to inject it once or twice daily. These long-acting insulins are "peakless" which means that they try and maintain the same glucose level throughout the day, unlike the fast acting insulins which result in a rapid decrease in blood sugar.

Bolus insulin - A bolus is a medical term for a single dose. Bolus insulin is given when you eat food in order to counteract the rapid increase in blood glucose after a meal. Bolus insulins are typically fast-acting, some of which start bringing down blood glucose in a matter of minutes. They do not remain in your system for long, being metabolized and excreted out of the body usually within a few hours.

So, to summarise... basal insulin keeps your blood sugar stable in the absence of food, but when you eat you need to take a bolus of fast acting insulin in order to counteract the sudden increase in blood sugar which comes from the breakdown of carbohydrate into glucose.

When Is Insulin Needed?

Insulin is always necessary for the treatment of type 1 diabetes, because there is a complete lack of the hormone in these patients. Type 2 diabetics do not usually require insulin until the disease has progressed to a point where the patient has become highly resistant to insulin, or when oral antidiabetic medications are no longer enough to keep blood glucose levels down.

A patient with insulin dependent type 2 diabetes has to use insulin in the same way as type 1 diabetics. However, there is a difference in that type 2 diabetics usually have to take much larger doses of insulin than type 1 patients because they have become so resistant to the effects of insulin.

For many type 2 diabetics, the addition of a long acting (basal) insulin such as Lantus or Levemir is usually enough to provide enough help to assist the body's own insulin in doing its job. If this is still not effective enough, a basal dose can be taken in addition to fast acting boluses of insulin at mealtimes.

Insulin Mixtures

These come premixed under certain brand names, a popular one is a 70/30 mix (70% long acting, 30% fast acting) called humulin or mixtard. These are usually taken before breakfast and supper.

However, the combination of basal and bolus injections provides much tighter glucose control and is a more flexible system than taking premixed insulin. This is because you can vary the amount and timing of the bolus to match what type of food you eat and when you eat it.

With mixtures of insulin such as the 70/30 mix, you have to take it on a rigid schedule, and you can only eat a certain number of carbohydrates each day and at a scheduled time. You are not able to vary the timing of the injections because they contain both slow acting and fast acting insulin, and you are not able to eat more or less food depending on how hungry you are that day.

How to Inject Insulin

Depending on the insulin regime prescribed by your doctor, you may have to inject insulin via a traditional syringe. However, the majority of patients now are using injection pens which come pre-filled with insulin as they are much easier to use. In either case, the following basics apply:

Step 1: If using a syringe, roll the insulin vial (or the syringe itself if it has been pre-filled) between the palms of your hands a number of times before filling the syringe to redistribute any particles that may have settled to the bottom. This ensures an even concentration of insulin in each dose. The same applies to insulin pens, but they should also be shaken as most pens have a small glass ball inside which can move around and mix the insulin thoroughly.

Step 2: Choose an injection site and pinch the skin slightly. Position the syringe or pen so that the insulin is injected under the fatty layer of the skin. Note that a 45 degree angle is best for children and adults who are very thin, otherwise a 90 degree angle may be more appropriate.

Step 3: You should rotate your injection site regularly. Insulin is best absorbed through the abdominal area so rotating injection sites in this area is ideal. You could visualize your abdomen as a grid of 8 squares. Assign to each square a particular day and change to a new one each day of the week.

Insulin Injection Tips

1. Subsequent injections should be delivered at least 1 inch away from the previous injection site.

2. It is not necessary to disinfect the injection site with an alcohol swab as long as your skin is clean.

3. If necessary, insulin may be injected through clothing, but this is not recommended.

4. Never shake a vial of insulin as this creates air bubbles which can clog the syringe.

5. Never mix one type of insulin with another in a single syringe. This can make it's effects erratic.

6. Try not to inject insulin into muscle tissue. It is painful and the insulin is absorbed too quickly and cause hypoglycemia.

Insulin Pumps

Insulin pumps are normally used in type 1 diabetes however they can work as effectively for insulin dependent type 2 diabetics also.

Some advantages of using an insulin pump include:

You change your infusion site once every 3 days, so if you have a dislike of needles, insulin pumping is better than having to inject yourself times a day.

You will use less insulin with a pump than on injections. Insulin pumps only use fast acting insulin which is more efficient than the slow acting types. Typically you use 20% less insulin when using a pump.

Because you have more control of the amount of insulin you take, if you are motivated, you can achieve much lower HbA1c (glucose average) than with injections. This improved control is due to the fact you can take doses that are not whole units, but fractions of a unit.

A new development in the area of insulin pumps is the advent of the artificial pancreas. This device combines an insulin pump with a continuous blood glucose meter, and automatically calculates how much insulin you need, minute by minute. This device is not currently on the market, but foundations such as the JDRF have invested a lot of money into it's R&D. Human trials are currently underway.

Is an Insulin Pump Right For Me?

Not everyone is suited to pump therapy, and it usually reserved for cases of type 1 diabetes or insulin dependent type 2 diabetes. In order to be successful at using an insulin pump:

• You need to be good at counting carbohydrates. You have to manually program the pump with the number of carbohydrates you are going to eat. It then calculates the dose of insulin to give you.
• You need to be comfortable working with technology. If you are unable to basic devices such as a cell phone, then the insulin pump is not for you. However, as you are reading this information on your computer, this is likely not the case.
• You need to be patient in order to give the pump a chance to impress you. It usually takes at least a week or two before your glucose levels reach a healthy level. It will also be at least several more weeks after that before you become confidant with adjusting the device.
• You need to have a cool head rather than anxiety prone. When your glucose level starts to seem a little scary you have to quickly figure out what changes you need to make. Your doctor will be able to assist you with the learning curve at first, but you will eventually have to cope with the device on your own as the lag time between seeing a problem and getting help is too long for another person to control your pump for you.
• Finally, you must be willing to test your blood glucose level with a glucometer about 8 times per day and more often when you are making adjustments to your routine.