Diabetes (Advanced Level)

Age Range 16-19
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  • Diabetes 16+
  • Type 1 and Type 2 diabetes
  • Regulating blood glucose levels
  • Diagnosis of diabetes
  • Discovery of Insulin
  • Insulin preparations
  • Islets of Langerhans
  • Making human insulin
  • Gene therapy for diabetes
  • Quiz

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Type 1 and Type 2 diabetes

There are approximately 180 million people worldwide who have diabetes and 2.5 million of these live in the UK. Up to one in five people with diabetes are unaware that they have the condition.

Diabetes can be successfully managed, but it is a chronic disorder which currently does not have a cure. It has several long-term health effects. This is especially true if blood glucose levels are poorly controlled in an individual.

Type 1 diabetes

Type 1 diabetes is an autoimmune disease and accounts for up to 10% of diabetes cases in the UK. It typically develops before the age of 40 and occurs when the pancreas can no longer produce insulin.

There are two types of cells in the pancreas. Exocrine cells are responsible for the production and secretion of digestive enzymes. These pass along the pancreatic duct into the duodenum. These cells are not usually affected in diabetes.

The pancreas also contains groups of cells called the islets of Langerhans. These cells release their products directly into the blood and so are a form of endocrine gland. Two hormones are produced in these islets. Insulin is made in beta cells and glucagon in alpha cells.

Type 1 diabetes develops when the person's own immune system destroys the beta cells. As a result insulin is no longer produced and blood sugar levels rise. This leads to the rapid onset of the symptoms of diabetes, including fatigue, unquenchable thirst, weight loss and the production of large volumes of urine.

The risk of developing type 1 diabetes has recently been linked with genetic factors and may be associated with lifestyle factors such as diet and exercise.

Type 1 diabetes is treated by insulin injections alongside a healthy diet and regular exercise. People with type 1 diabetes are usually required to take either two or four injections of insulin every day. These injections of insulin are vital to keep these people alive.

Type 2 diabetes

Type 2 diabetes is a disorder that is increasing in both developed and developing nations as unhealthy diets and lifestyles become more common. It develops when the body can still make some insulin but not enough, or when the insulin that is produced does not work properly (known as insulin resistance). In most cases this is linked with the person being overweight. Type 2 diabetes usually occurs in people over the age of 40. In South Asian and African-Caribbean people it often appears after the age of 25. Recently more children are being diagnosed with the condition. Type 2 diabetes is more common than type 1 diabetes accounting for 85-95% of people with diabetes.

Many factors influence the development of type 2 diabetes; such as an inherited predisposition to diabetes and diets high in saturated fats, sugar and low in fibre. Being overweight also increases the chance of developing type 2 diabetes. Abdominal fat cells release fatty acids into the blood that stimulate the liver to release glucose and triglycerides. This process is therefore increased in overweight people with greater numbers of abdominal fat cells. Over a long period, muscles become insensitive to insulin and beta cells are destroyed.

Obese man

Diabetes is increasing in developed nations. Obesity is linked with an increased risk of type 2 diabetes

Courtesy of: Anthea Sieveking / Wellcome Images

Obesity causes raised fatty acid levels which can cause diabetes.

Obesity causes raised fatty acid levels which can cause diabetes

Type 2 diabetes accounts for around 90% of cases in the UK. It typically develops in the over 40's and can be treated using combinations of lifestyle changes (diet and exercise), oral medicines and daily, long acting, insulin injections.

Healthy diet

  • Regular meals with foods that contain starch (bread, pasta, potatoes and rice) and decreased consumption of processed foods to maintain a stable blood sugar level.
  • Reduced consumption of sugary foods like carbonated drinks, cakes and sweets.
  • If overweight/obese, losing weight will help to control the disorder.

Medicines

  • Bind to receptors on beta cells and stimulate the release of insulin.
  • Sensitize the liver, fat and muscle cells to the insulin that is available.
  • Reduce the breakdown of glycogen into glucose in the liver.
  • Enzyme-inhibitors slow the breakdown of complex carbohydrates in the digestive system.

Regular exercise

  • Helps the body to regulate its blood glucose levels.
  • Helps to maintain a healthy weight.
  • Improves blood pressure and lessens the chances of circulation problems.

Recent research has shown that it is possible to prevent diabetes in some people who are at high risk of developing the disease. For example, individuals in the Finnish Diabetes Prevention Study took part in an intensive lifestyle programme focussed on changing diet and physical activity behaviour. Over four years, these individuals were 60% less likely to develop diabetes than individuals who did not take part in the programme.

More detailed information on diabetes for young people

Question 1


a)
What type of cells are found in the Islets of Langerhans?
b)
What is an auto-immune disorder?
c)
What is one of the causes of insulin-resistance in type 2 diabetes?
d)
Which part of the pancreas is resonsible for producing insulin?

Acarbose
This type 2 diabetes medication is not much used now.
Amino acids
The basic building blocks of proteins. There are twenty amino acids used, in different combinations, to make every protein required by the human body.
ATP (adenosine triphosphate)
A small organic non-protein molecule that is a source of chemical energy within a cell.
Autoimmune disease
A disorder where the body's immune system behaves abnormally and starts attacking its own cells
Autopsies
The study of the human body to investigate how a disease or injury leads to death
Cardiovascular disorders
Diseases linked to the heart and its blood vessels, for example heart disease and stroke
Diabetic ketoacidosis (DKA)
When glucose is high in the blood but unable to enter cells, the body starts using stores of fat for energy, which results in the production of acidic ketones as a by-product. If ketone levels rise unchecked a hyperglycaemic coma can result which may be fatal.
Disulfide bridge
A covalent S-S bond that joins two cysteine amino acids together, also called an SS-bond or disulfide bond.
Duodenum
Within the human body this is the first 25 - 30cm long section of the small intestine.
Embryo
The name for a group of cells that are developing into a foetus. In humans this is from implantation to the 8th week of development
Endocrine gland
A gland which secretes hormones straight into the bloodstream rather into the blood via a tube or duct.
Enzyme
Biological catalysts that speed up chemical reactions.
Exocrine cells
Cells found in the exocrine glands that secrete hormones into ducts, as opposed to straight into the bloodstream.
Fermentation
Process where microorganisms are cultured so that they reproduce and increase in quantity
Fatty acid
Large molecule consisting of a carboxylic acid (RCOOH) with the 'R' being a long unbranched hydrocarbon chain.
Gastrointestinal
Relating to the body's digestive system, including the stomach and intestines.
Gene
A short piece of DNA which is responsible for the inheritance of a particular characteristic. It codes for the production of a specific protein
Gene therapy
A new, experimental method of fighting disease by replacing a defective gene with a healthy gene
Genetic engineering
A general name for the processes which scientists use to produce desired characteristics or substances that are in short supply, such as human insulin
Glucagon
A hormone produced by the pancreas. It causes the liver to convert glycogen back to glucose and to release glucose into the bloodstream.
Glucose
A type of sugar: a monosaccharide with 6 carbon atoms (a hexose sugar)
Glycogen
A polysaccharide,
(C 6 H 10 O 5 ) n , that is stored in the liver and in muscles and can be converted back into glucose when needed by the body.
Harvested
The process by which a useful substance is extracted
Home Office
The UK government department responsible for regulating the use of animals in scientific research
Hormone
A chemical messenger produced by a particular gland or cells of the endocrine system. Hormones are transported throughout the body in the blood stream but they produce a response only in specific target cells
Hydrogen bond
An intermolecular force between hydrogen, when it is covalently bonded to a highly electronegative atom (fluorine, oxygen or nitrogen), and an oxygen, nitrogen or fluorine atom on another molecule.
Hyperglycaemic
This is the term used when the blood glucose level is too high (more than 10 mmol/l)
Hypoglycaemic
This is the term used when the blood glucose level is too low (less than 4 mmol/l)
Immune system
The body's own system for protecting it against disease (where it produces antibodies to attack invading pathogens)
In vitro fertilisation
A process where the egg is fertilised outside of the body and then transferred back into the uterus to develop normally
Insulin
A hormone produced by the pancreas. It is active in controlling blood glucose levels as it allows cells in the body to take in and store glucose.
Liver
A large organ in the upper abdomen which manufactures, stores and breaks down substances as required by the body
Mitochondria
Organelles within cells that produce ATP, used as a store of chemical energy. Often called the cell's powerhouse.
Mucosa
The membrane that lines the body's cavities and passages. In certain areas, such as the nose and mouth, this membrane absorbs substances and secretes mucus.
Non-animal alternatives
Processes such as cell culture, computer modelling, imaging and microdosing of human volunteers that can give information on potential harmful effects of a substance
Obesity
A disorder where an excessive amount of fat has accumulated in the body. It results when the energy taken in as food is stored in the body instead of being used up through activity
Organelles
A distinct part of the cell, such as the nucleus, ribosome or mitochondrion, which has structure and function.
Pancreas
An endocrine gland which produces insulin
Polysaccharides
Complex carbohydrates consisting of more than one sugar molecule.
Proteins
A polymer made up of amino acids joined by peptide bonds. The amino acids present and the order in which they occur vary from one protein to another.
Receptors
Protein molecules attached to cells that only bind to specific molecules with a particular structure.
Respiration
The biochemical process by which the cells in the body release energy
Messenger RNA (ribonucleic acid)
Single chains of nucleotide units that transmit the information from the DNA inside the cell's nucleus to the ribosomes in the cytoplasm which synthesise the required proteins.
Ribosome
Small organelles that synthesise proteins.
Rough endoplasmic reticulum
A network of membranes within a cell which has ribosomes attached to it. They are important in the synthesis and transportation of proteins.
Stem cells
Undifferentiated cells that can develop into a diverse range of specialised cell types.
Sterile
Uncontaminated by microorganisms
Triglycerides
The most common lipid found in nature and consists of a single glycerol molecule bonded to three fatty acids.
UK Law [for animal testing]
Animal welfare is regulated in the UK by the Animal (Scientific Procedures) Act 1986
Vesicle
A small sac that stores or transports substances inside a cell.
X-ray crystallography
A technique that uses the diffraction of X-rays to determine the molecular structure of a crystalline substance.


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