Diabetes (Advanced Level)

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Diagnosis of diabetes

Type 1 diabetes

The onset of type 1 diabetes is rapid and its symptoms are likely to be noticed through:

Excessive thirst
Weight loss
Drowsiness
In extreme cases, coma.
Blood glucose level above 10 millimoles per litre (mmol/l).
Muscle cramps
Gastrointestinal symptoms such as nausea and vomiting, abdominal pain and changes in bowel movements
Diabetic ketoacidosis (DKA)
Polyuria (excessive urine production)
Urinary tract infections

A simple test strip can indicate the presence of glucose in the urine.

Images courtesy of: Wellcome Images

Type 2 diabetes

This form of diabetes develops much more gradually and so symptoms may not be apparent for many years. It is often diagnosed during healthy screening tests where the blood sugar level is found to be elevated despite there being no symptoms of diabetes.

Oral Glucose Tolerance Test (OGTT)

Simple blood and urine tests may be sufficient to diagnose diabetes in some people. Others may have to take an oral glucose tolerance test (OGTT) if other blood and urine tests are inconclusive.

Patients are not allowed to eat for at least 12 hours before the test. A blood sample is then taken to measure the patient's fasting blood glucose level.

They are then given a drink containing 75g of glucose. This is quickly absorbed and their blood glucose level is measured over the next two hours.

Individuals with diabetes rapidly become hyperglycaemic and their blood glucose level remains above normal.

Healthy individuals will release insulin to store the excess glucose and return their blood glucose level to normal.

Blood glucose in the diabetic rises and stays above normal.
The healthy person regulates their glucose back to normal.

Plasma venous glucose concentrations used for diagnosis of diabetes

	Plasma (mmol / l)
	Venous
Fasting	≥ 7
2 hours post-glucose	≥ 11.1

Question 3

In the UK, there are significant variations in the frequency of type 2 diabetes between different population groups.

Look at the graph and answer the question.

Rates of diabetes in different population groups

Rates of diabetes in different ethnic groups in England

The graph shows the incidence of diabetes in adults over the age of 16 from different population groups (type 1 plus type 2). Describe the likely factors that influence the different rates of diabetes. Suggest how these factors could be further investigated.

Click to see what our expert suggests

Factors may be:

Most groups exhibit greater rates than when the population as a whole is considered.
Women are generally less likely to have diabetes than men are. However Pakistani women have a higher rate of diabetes than Pakistani men.
Genetic differences are likely to be a major contributing factor. Black Caribbean, Pakistani, Indian and Bangladeshi groups all have high levels of diabetes. Chinese, Black African and Irish are closer to the population average.
Diet could play a part, as ethnic groups may have different diets.
As families relocate from Asia to Europe, their lifestyle and diet may change to ones that increase the risk of developing diabetes.

Further investigations could include:

Genetic screening of families where someone has diabetes could lead to the identification of family members who have genes that make them susceptible to diabetes.
Analyse the diets of groups / families that have a higher incidence of diabetes. E.g. what proportions of diet is high in fat, sugar etc. Compare with groups that have a lower incidence.
Investigate lifestyle â€“ activity, obesity etc.
Look at incidence of diabetes in regions where groups originated. Is the incidence of diabetes the same or different? If different, look for differences in diet and lifestyle that could explain the change in incidence.

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.