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Insulin pumps provide a constant delivery of insulin to the patient throughout the day. |
Diabetes is a disease where the body is unable to sufficiently produce or effectively use the hormone insulin. Insulin is the key hormone that regulates the entry of glucose into the various cells of the body as a source of energy.
Without insulin, excessive amounts of glucose remain within the blood, resulting in a state of hyperglycaemia.
Prolonged exposure to hyperglycaemia is hazardous and may lead to complications such as blindness, kidney failure and heart attacks.
Many patients with diabetes require insulin as a form of treatment to correct the state of hyperglycaemia effectively.
Insulin
In a normal individual, insulin is produced by the beta cells of the pancreas and released in response to a meal or a rise in the blood glucose level. A smaller amount of insulin is also released in a constant and pulsatile fashion throughout the day and night to regulate the body’s resting need of glucose.
In type 1 diabetes, patients depend on external insulin shots for survival as there is a total deficit of insulin from the body.
Type 2 diabetes patients have insulin but lack sufficient amounts and are unable to use them properly. These patients may be treated with oral pills but require insulin shots if the body fails to meet the demand for insulin secretion.
Insulin cannot be taken orally as a pill because it would be broken down during digestion, just like proteins.
Types of insulin
The discovery of insulin in 1920s won both Dr Frederick Banting and his medical student, Dr Charles Best, a Nobel Prize. The discovery was first announced to the world on May 3, 1922.
Since then, for many years, the insulin used by people with diabetes had been isolated from pig and bovine sources.
Synthetic human insulin has been available only in the last two decades and constitutes the more widely used commercial preparation today.
Apart from the source, types of insulin differ with regards to how fast they start to work and how long the effect lasts. Accordingly, insulin may be classified as rapid acting, short acting, intermediate acting, long acting and premixed insulin.
Rapid acting insulin has an extremely fast absorption and has a peak action within 30 minutes upon administration. The duration of action lasts one to two hours, after which the level falls rapidly. It is conveniently taken just before a meal to control the post-meal glucose surge.
Short acting insulin has a peak action at about two to three hours after administration and the duration of action lasts for six to eight hours in most individuals. Often taken about 30-45 minutes before a meal, it is also used to control the large rise of blood glucose after a meal.
Intermediate acting insulin has a peak action seven to nine hours after injection and the action lasts up to 12-16 hours thereafter. It is often used at bedtime to control the morning glucose of the next day.
The long acting insulin has a peak action after 10-12 hours of injection and the effect lingers for 16-20 hours later.
Premixed insulin consists of a fixed mixture of rapid or short acting and intermediate acting insulin in a single preparation lasting 16-20 hours.
Newer long acting insulin analogues are now available where the effect lasts for a complete 24 hours. These are also called basal insulin preparations.
The choice of the insulin to be prescribed depends on many factors, including the treatment goals, age, lifestyle, meal plans, risk of low blood glucose (hypoglycaemia) and the financial status of the patient.
Insulin delivery devices
Traditionally, insulin was administered with a needle and a syringe. Syringes varied in the capacity and with the needle sizes. However, they were not very convenient, hygienic or comfortable for use.
Today, insulin delivery systems have evolved towards a more comfortable, hygienic and convenient method of administration with disposable insulin pens. These are more discrete and do not need to be replaced once used. Finer needles are used and injections are almost painless compared to the traditionally used large bored needles.
Insulin pumps are also available and provide a constant delivery of insulin to the patient throughout the day. The development of newer delivery systems such as insulin patches is ongoing and anticipated.
Treating diabetes with insulin
Consensus guidelines between the American Diabetes Association (ADA) and the European Association for the Study of Diabetes (EASD) on the management of type 2 diabetes advocate that a basal insulin should be started early in the disease to achieve good glycaemic control of HbA1c <>
Minimising the time spent in a state of poor glycaemic control reduces the risk of developing the complications related to diabetes and improves the overall well-being of the patient.
Modern day preparations of insulin differ drastically from the preparations in the past in terms of insulin delivery, effectiveness and safety.
In addition, basal insulin preparations such as insulin glargine are associated with a low risk of hypoglycaemia and weight gain to the patient.
Since the discovery of insulin close to a century ago, insulin still remains as the most potent agent to reduce the glycosylated haemoglobin levels (HbA1c) in diabetes patients compared to all other anti diabetic agents available.
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