Why diabetes occurs
Diabetes occurs because the body can’t use glucose properly, either owing to a lack of the hormone insulin or because the insulin available doesn’t work effectively.
The full name diabetes mellitus derives from the Greek word diabetes meaning siphon – to pass through – and mellitus, the Latin for honeyed or sweet. This is because not only is excess sugar found in the blood but it may also appear in the urine, hence it being known in the 17th century as the ‘pissing evil’.
According to the charity Diabetes UK, more than two million people in the UK have the condition and up to 750,000 more are believed to have it without realising they do.
More than three-quarters of people with diabetes have type 2 diabetes mellitus. This used to be known as non-insulin dependent diabetes mellitus (NIDDM) or maturity-onset diabetes mellitus. The number of people with type 2 diabetes is rapidly increasing as it commoner in the overweight and obese, which is itself a growing problem.
The remainder have type 1 diabetes mellitus, which used to be known as insulin-dependent diabetes mellitus.
Type 1 diabetes
In type 1 diabetes, the body is unable to produce any insulin.
It usually starts in childhood or young adulthood, and is treated with diet control and insulin injections.
Type 2 diabetes
In type 2 diabetes, not enough insulin is produced or the insulin that is made by the body doesn’t work properly.
It tends to affect people as they get older and usually appears after the age of 40, but increasingly is seen in younger, overweight people.
Normal blood sugar control
The body converts glucose from food into energy. Glucose comes ready made in sweet foods such as sweets and cakes, or from starchy foods such as potatoes, pasta or bread once they’re digested. The liver is also able to manufacture glucose.
Under normal circumstances, the hormone insulin, which is made by the pancreas, carefully regulates how much glucose is in the blood. Insulin stimulates cells to absorb enough glucose from the blood for the energy, or fuel, that they need. Insulin also stimulates the liver to absorb and store any glucose that’s left over.
After a meal, the amount of glucose in the blood rises, which triggers the release of insulin. When blood glucose levels fall, during exercise for example, insulin levels fall too.
A second hormone manufactured by the pancreas is called glucagon. It stimulates the liver to release glucose when it’s needed, and this raises the level of glucose in the blood.
Insulin is manufactured and stored in the pancreas, which is a thin gland about 15cm (6in) long that lies crosswise behind the stomach. It’s often described as being two glands in one, since in addition to making insulin it also produces enzymes that are vital for digestion of food.
These include lipase, which helps to digest fat, and amylase that helps to digest starchy foods. It also releases ‘bicarbonate of soda’ to neutralise any stomach acid that may otherwise damage the lining of the gut.
Diabetes that isn’t controlled can cause many serious long-term problems. Excess glucose in the blood can damage the blood vessels, contributing to heart disease, strokes, kidney disease, impotence and nerve damage.
Uncontrolled diabetes is the most common cause of blindness in people of working age. People with diabetes are also 15 per cent more likely to have an amputation than people without the condition.
In most cases, it’s possible to reduce the risk of such complications by following medical advice and keeping diabetes under control. It’s vitally important for people with diabetes to check their glucose levels regularly at home and to attend GP, diabetes nurse or hospital check-ups, so any problems can be detected and treated early.