Diabetes (Advanced Level)

Age Range 16-19

Page 5 of 10

  • 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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Discovery of Insulin

Person injecting insulin

Injecting insulin allows individuals with diabetes to control their blood sugar levels.

In 1921 two researchers, Fred Banting and Charles Best, were the first to discover insulin and use it to treat diabetes.

Animal Testing

At the time that Banting and Best were looking for a cure for diabetes, there were no alternatives but to perform their experiments using animals.

To test their theory Banting and Best used 10 dogs. They made the dogs diabetic and then investigated treatments for the diabetes. The result of their research has saved the lives of millions of people.

Banting and Best's discovery of insulin

Investigations using isolated insulin from dog pancreas

Some people have very strong opinions about testing medicines on animals. Today the use of animals is very tightly regulated and only allowed in circumstances where there are no other viable alternatives. Decide on a set of rules that should govern whether testing can take place or not.

Click here to see what the current UK law says about animal research.


Banting and Best did not know the chemical structure of insulin. In 1955, Fred Sanger determined its amino acid structure and in 1969, Dorothy Hodgkin used X-ray crystallography to find its three-dimensional structure.

The insulin molecule acts by attaching to cell-surface receptors on its target cells. Its three-dimensional structure enables it to attach to these receptors. The shape of the insulin molecule is determined by the way the protein chains fold around each other due to hydrogen bonds and disulfide bridges .

Insulin is a protein made up of two amino acid chains.

Chemical structure of insulin
3-d model of insulin

Molecular model of insulin molecule, ribbon

3-d model of insulin

This model shows the three-dimensional structure of insulin. It is a complex protein hormone

Image courtesy of: T. Blundell & N. Campillo / Wellcome Images

Protein structure

The three dimensional structure of protein is described using four categories:

  • Primary
    Amino acid sequence of the polypeptide chain. e.g. amino acids in insulin's A and B chains.
  • Secondary
    How the amino acid chain folds back onto itself. Typically beta sheets or alpha helices.
  • Tertiary
    Folds in the beta sheets or helixes to give overall structure of the polypeptide chain.
  • Quaternary
    Some proteins are made of more than one polypeptide chain. These are joined to make the functioning protein. e.g. insulin's A and B chains are joined by disulfide bridges.

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
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.
Within the human body this is the first 25 - 30cm long section of the small intestine.
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.
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.
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.
Relating to the body's digestive system, including the stomach and intestines.
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
A hormone produced by the pancreas. It causes the liver to convert glycogen back to glucose and to release glucose into the bloodstream.
A type of sugar: a monosaccharide with 6 carbon atoms (a hexose sugar)
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.
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
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.
This is the term used when the blood glucose level is too high (more than 10 mmol/l)
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
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.
A large organ in the upper abdomen which manufactures, stores and breaks down substances as required by the body
Organelles within cells that produce ATP, used as a store of chemical energy. Often called the cell's powerhouse.
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
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
A distinct part of the cell, such as the nucleus, ribosome or mitochondrion, which has structure and function.
An endocrine gland which produces insulin
Complex carbohydrates consisting of more than one sugar molecule.
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.
Protein molecules attached to cells that only bind to specific molecules with a particular structure.
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.
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.
Uncontaminated by microorganisms
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
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.