The level of glucose in the blood is monitored and controlled by the action of a hormone called insulin. After consumption of carbohydrates, when levels of glucose are high in the blood, insulin signals to the body's cells to absorb glucose for energy or storage. As the cells sponge up the blood glucose, levels of glucose in the blood fall back to the level that they were at before the food was eaten.

There are two types of diabetes. In Type 1 diabetes (also know as insulin dependent diabetes (IDDM)) the cells cannot absorb glucose as the body does not make enough insulin. This form of diabetes is treated with insulin injections. In Type 2 diabetes (also known as non insulin dependent diabetes (NIDDM)) the cells do not respond well to insulin's signal to take up the blood glucose. This is called insulin resistance. The blood glucose and insulin levels remain at high levels in the blood and with time, insulin production stops. Type 2 diabetes has been linked to high blood pressure, a lowering of HDL cholesterol and heart disease.

Insulin resistance as seen in Type 2 diabetes is thought to be caused by a combination of genetic factors, a sedentary lifestyle, being overweight and a diet that encourages high levels of blood glucose after eating. To prevent the onset of Type 2 diabetes-people are encouraged to cut back on refined grains and eat more whole grains as part of a balanced diet. There is no evidence that high consumption of sugars causes diabetes, although Type 2 diabetes is associated with a person being overweight, which may be caused by over-consumption of high fat/sugar foods.

Symptoms of diabetes are often caused by the blood glucose level being raised above normal (hyperglycaemia). Symptoms are often severe and generally lead to a quick diagnosis. They may include tiredness, extreme weight loss, extreme thirst and frequent passing of urine.

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