हिन्दी (Hindi) मे पढ़िये
In diabetes mellitus there may be a total or partial deficiency of insulin secretion from the beta cells of the pancreas. Hence a logical treatment of diabetes is replacement of insulin from external sources. This was first made possible by the work of Banting, Best and MacLeod who won the Nobel Prize for Physiology and Medicine in 1923 for their contribution. They extracted insulin from the pancreas of a dog and injected into a diabetic human being with dramatic result. They found that insulin could not be given orally as it was degraded in the gastrointestinal tract (the tube into which food goes and is processed for use by the body). Initially insulin used to be extracted from animal (bovine and porcine pancreas). With improvement in production technology pure animal insulin could be produced. Nowadays human insulin can be produced by recombinant DNA technology. But it is more expensive than animal insulin. Though use of human insulin is in vogue animal insulin can be used with similar effect at a cheaper price. It is definitely suitable for people in our country who have difficulty in purchasing insulin.
Why does my doctor prescribe me insulin?
Most patients prefer oral drugs to insulin which needs to be injected. Neverthless, insulin has to be prescribed to some individuals. Certain conditions where insulin is required are:
1. When blood glucose levels are very high
2. Pregnant women
3. Kidney, liver or heart disease
4. Associated infections like tuberculosis
5. During surgery
6. When a patient with diabetes is hospitalized due to serious illness.
7. When blood glucose cannot be controlled with oral drugs any more
8. Type 1 diabetes mellitus where the pancreas cannot secrete any insulin and oral medication has no effect.
The basic defect in type 2 diabetes mellitus is progressive failure of the beta cells of the pancreas to secrete insulin. In the earlier stages this defect can be overcome by drugs which help in the release of insulin or its action. However when the deficiency crosses a threshold insulin must be supplanted from external sources.
Do I have to keep on taking insulin once I start?
If insulin is started because of a condition which is temporary like pregnancy or tuberculosis then oral drugs may be restarted later on. However, if the condition is permanent like chronic kidney disease or pancreatic failure then it has to be continued lifelong.
It is a common perception that it is possible to be habituated to insulin. One cannot become habituated to insulin. Unlike smoking, sedatives (benzodiazepines like diazepam), alcohol or ganja insulin in not habit forming. The reason it has to be continued lifelong is totally different. It is because the body is unable to produce it in required quantity. Furthermore insulin is essential for the functions of the body without which disease and death is inevitable.
What is the technique of taking insulin?
Insulin is injected into the fat beneath the skin. This technique of injection is called a subcutaneous injection. It may be injected into areas like the abdomen, upper arm and thighs where there is plenty of fat. The skin is pinched up in a fold and the needle is introduced at 90 degrees to the skin and the requisite dose injected in. There are many types of devices to inject insulin like syringes, pen devices, pumps. Pen devices are most suitable for home use by the patient. But they come at higher price.
The dose of insulin is calculated in units. In India Insulin is available in two strengths – 40 IU/ml and 100 IU/ml. Two different syringes are available for administering them – 40 IU/ml and 100 IU/ml. This causes confusion among patients. If the appropriate syringe is not used for a particular insulin then it may lead to an under- or over-dose. Repeated injection of insulin over the same site may cause local hypertrophy (increased size of the cells locally). This side effect may be avoided by rotating the site of insulin injection from time to time.
Why are there so many types of insulin available in the market?
In the human body there is only one type of insulin. But for patients we use different types of insulin. The main reason behind this is that we cannot mimic the sophisticated pattern of insulin secretion maintained by the human body. The human pancreatic beta cells secrete a basal amount of insulin and in addition secrete more or less according to necessity, such as after meals. The two basic forms of insulin available are short acting and long acting forms. The short acting insulin is clear or transparent and the long acting insulin is cloudy. The long acting insulin is prepared by mixing protamine with insulin which delays its passage of from the subcutaneous tissue (layer of fat beneath the skin) to the blood. Short acting insulin is given 15-30 minutes before meals so that it neutralizes the rise of blood glucose that occurs after a meal. Long acting insulin acts almost throughout the day and if given once daily maintains the basal or fasting blood glucose level at normal. It is usually given at bedtime and has no relation to meals. To complicate matters mixed insulins are available containing different proportions of short acting and long acting insulin. These mixed insulins are very popular and are used widely.
Recently tailor made insulins have arrived. These insulins are minor variations of the original insulin molecule. As we know insulin is a protein and comprises of amino acids. Even the change of a single amino acid will change its properties. This principle is exploited here and minor changes in the amino acid sequence has produced insulin lispro and insulin aspart which are very short acting and insulin glargine which is very long acting. The advantages of these formulations is that the ultra-short acting insulins may be given just before meals in which the patient need not wait before eating thus saving much inconvenience and the ultra-long acting insulins keep on acting for 24 hours fully (actually the long acting insulin mentioned earlier does not cover the full day). However these formulations are relatively expensive.
How should I keep the insulin?
Insulin vials may be kept in a cool dark place (25 degrees Centigrade) for 4-6 weeks. If kept in the refrigerator at 4 degrees Centigrade it may be used till its expiry date. Exposure of the insulin vial to heat or microwaves will cause its degradation.
What are the side effects of insulin?
The most dreaded side effect of insulin is too much lowering of blood glucose (hypoglycaemia). This phenomenon may lead to death in a very short time. Repeated episodes of hypoglycaemia in the elderly may lead to permanent brain damage.
Why does the doctor keep on changing my dose of insulin?
The appropriate dose of insulin in a patient is arrived at by trial and error. It takes time to do this and the patient has to come to the doctor many times before an optimum dose is achieved. Even after that the dose of insulin has to be regulated if the patient has additional illnesses like tuberculosis or is hospitalized. So patients on insulin treatment require frequent blood tests (more needle pricks!) specially so during the period of titration of dose of insulin. During this period it may be useful for the patient to test his own blood glucose at home with a glucometer. This is known as self monitoring of blood glucose. These tests are costly and painful but certainly useful in the titration of insulin dose and certainly in the timely prevention of hypoglycaemia.