Introduction

Reminders

Insulin reduces the concentration of glucose in your blood - triggers the conversion of glucose into glycogen - your principal chemical potential energy store.

Lack of insulin can lead to dangerously high glucose levels in your blood.

See (1) The need to control the blood sugar level - health issues

What is diabetes?

Diabetes conditions occur in people whose body, for one reason or another, does not produce enough insulin to adequately control the level of glucose in the bloodstream.

Diabetes is the failure of the homeostasis control system described in the previous section i.e. the negative feedback system based on the hormones insulin and glucagon - diagram below.

Type 1 Diabetes - caused by insulin deficiency

Type 1 diabetes is a disease in which a person’s blood glucose concentration may rise to a high level because the pancreas does not produce enough of the hormone insulin.

What causes type 1 diabetes? The insulin producing cells are destroyed - this can be due to an autoimmune condition in which the immune system mistakenly attacks the body's own healthy cells.

Type 1 diabetes is caused by a lack of insulin, the hormone which controls the level of glucose in the blood - too little may be produced or non at all - a potentially dangerous situation.

Without insulin secretion the blood glucose level to rise to potentially lethal levels.

Without insulin, the body's cells are unable to utilise glucose, whose level becomes dangerously high and excreted in the urine.

The graph on the right compares the glucose concentration in the blood after a Type 1 diabetic and a non-diabetic person after each is given a sugary drink.

The diabetic, not producing insulin, has no control over the glucose level which rises well above that normally required. It remains too high, but can be lowered if insulin is injected into the body.

The non-diabetic produces insulin from the pancreas in response to the rising concentration of glucose, which goes well above normal. The glucose level then falls back to normal as the body's cells take up the glucose (respiration or glycogen formation).

Note that if the supply of glucose is inadequate, the body's cells use fat and protein as alternative energy supplies.

If the diabetes is not controlled, a person can lose weight and lead to kidney failure and death.

Type 1 diabetes may be controlled partially by careful attention to diet and exercise, BUT injection of insulin, usually into the subcutaneous fat is required- insulin therapy must always be applied to type 1 diabetes patients.

Type 1 diabetes can be controlled by two strategies, and both may be required ..

There is NO CURE for Type 1 diabetes and it cannot be prevented.

(i) Avoid too much sugary foods and carbohydrates in the diet, sugars in particular, will cause a rapid rise in glucose levels which is difficult to remove without the presence of sufficient insulin - but diet management is not enough to cope with Type 1 diabetes.

(ii) Insulin therapy - injecting insulin, perhaps several times a day at meal times, which will make the liver and muscles remove excess glucose from the digested food - this makes sure the excess glucose is converted to glycogen, reducing the concentration in the blood.

This is an inconvenient, but very effective way, of keeping the blood sugar level in check.

The insulin is usually injected into the subcutaneous fatty tissue just under the skin.

You cannot take insulin orally as a pill or tablet because the enzymes in your stomach break it down before it can reach the bloodstream.

The amount of insulin required varies from individual to another - it depends on the body mass, diet and exercise they take - injecting too much insulin could lead to too low a level of glucose in the blood.

In Type 1 diabetes, the level of physical activity and diet affect the amount of insulin required.

The amount of insulin required by injection depends on the person's diet and level of physical activity.

A diabetic should minimise food rich in simple carbohydrates like glucose which can cause quite a rapid increase in blood sugar.

As well as controlling carbohydrate intake, taking regular exercise helps to use up some of the excess glucose from the blood.

It is dangerous to inject too much insulin because that could lead to dangerously low levels of glucose.

Insulin injections can greatly help diabetics in providing the necessary insulin but it can never be as successful as a properly functioning normal pancreas and diabetics can suffer from long-term health problems.

A healthy balanced diet, regular eating and regular exercise will both help to keep a diabetic in good health and minimise the amount of insulin needed.

Diabetics can have a pancreas transplant which, if successful, can theoretically avoid the need for insulin, but there is always the danger tissue rejection and costly immunosuppressive drugs must be taken (with the added complication of serious side-effects).

Monitoring your blood sugar levels

You can do a blood sugar level check by doing a finger-prick test, or by using an electronic blood sugar monitor called a flash glucose monitor or CGM.

You can do this several times a day – helping you keep an eye on your levels as you go about your life and help you work out what to eat and how much insulin medication to take.

Footnote on source of insulin

Insulin was once extracted from the pancreas of a pig or cow, but human insulin is now made genetic engineering and doesn't give the side effects experienced from patients using animal insulin.

I remember a class debate on the merits and ethical issues concerning the use of genetic modification (GM) engineering. A diabetic in the class took to task another student trying to take the 'moral high ground' in arguing how wrong it was to use GM for medical purposes (or any other purpose - on the grounds it was interfering with nature). So, can I please point out the millions of diabetic patients around the world whose lives are so much more improved by a 'slow release' genetic modification of the hormone insulin.

Type 2 Diabetes - caused by insulin resistance

The type 2 diabetes condition is

(i) When the pancreas doesn't make enough insulin to enable the body to respond effectively to rising glucose levels.

(ii) The person has become resistant to insulin so the body doesn't even respond appropriately to any of the hormone insulin present - its as if the body's cells have lost their sensitivity to changes

and both will cause the blood sugar level to rise to potentially lethal levels.

Test for Type 2 diabetes

One test is to ask the patient to refrain from eating and drinking for ~10 hours and the glucose level in the blood measured.

The patient is then given glucose and their blood reanalysed for its concentration 2 hours later.

If the patient's tolerance to glucose is lowered, the glucose will be above an acceptable level.

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