- Insulin Therapy
How to inject insulin
Insulin is injected by a small needle into the space under the skin, called subcutaneous space. Insulin can be injected by a syringe, or by a pen device hosts a smaller; thinner needle – such devices increase the convenience and decrease pain of injection. Common sites of injection are the abdomen, outer thigh and upper arm. The site of insulin injections must be changed from day to day. Injecting into the same area for several weeks can cause the skin in that area to become abnormal. Further injections into this abnormal area will have little or no effect.
Insulin injections do not depend on the age of the patient. Even small children as well as very elderly people are able to take insulin injections by themselves. When insulin is repeatedly injected into the same area, skin can become abnormal. This is patient who repeatedly injected insulin for several years into the same site on the thigh.
Insulin was earlier only derived from animals- examples are beef pork insulin. However, human insulin is the worldwide favourite now. Human insulin is manufactured in factories using a technology known as recombinant DNA method. However, human insulin, when injected behaves very differently as compared to when the pancreas produces it. As a result, scientists have been constantly searching for the perfect insulin. The result of these experiments was the creation of designer insulin, also called insulin analogues. These analogues are better able to mimic pancreatic insulin patterns. The long acting analogues provide the near perfect basal insulin, and the short acting analogue – provide the bolus spurts.
Premixed insulin combine short acting and long acting insulin in order to mimic the patterns. The most common preparation consist of 30% regular insulin and 70% intermediate acting insulin. These injections are given twice a day. They are very convenient to take and easy to use. In many diabetic subjects, they can control the blood sugars very well. However, some patients have elevated post –lunch glucose levels that this cannot control very effectively.
As shown in the table, the newer insulin are either ultra – short acting analogue or the long acting analogues. The former can be injected just before or after meals traditional short acting insulin have to be injected at bed time , but they can be given at any time of the day for a 24-hour coverage. The use of these insulin analogues lies in the fact that the dose can be increased aggressively without much fear of hypoglycaemia. Thus the patients can reach their targets more rapidly and accurately. Nowadays, it is said that the target for HbA1c (a measure of glucose control over 3 months) is < 6.5%. Never insulin suggest that more and more diabetics can reach and maintain these targets.
|Lispro||Ultra short acting||1||3-4|
|Aspart||Ultra short acting||1|
Regular and NPH insulin are human insulin, the rest are newer types of insulin called insulin analogues.
New Modalities of Insulin Therapy
Nowadays, for those with very difficult to control diabetes, insulin pump too can deliver insulin. The insulin pump is a pager like device that injects insulin 24 hours a day. A small motor pushes a piston that delivers insulin through a tube to an area under the skin. Glucose control, in the author’s experience, is very superior with pump therapy. However, not all patients are suitable for pump therapy. A qualified specialist required to choose the right patient for insulin pump treatment. In some cases, the pump is wirelessly hooked to a glucose sensing device and this predicts hypoglycaemia trends for the diabetic subject.
In addition, insulin inhalers are now available in United State. These insulin can control post-prandial glucose very well. The dose used for inhalation is very large, as only a small proportion of this actually enters the blood stream. These are very useful in subjects with needle phobia. Finally oral insulin and insulin patches are in various stages of drug development. Given the rapid strides being made in insulin delivery, it is expected that in the decades to come, the diabetic subject may not need to fear the pain of insulin injections!