Diabetes

Diabetes significantly increases the risk of coronary heart disease (CHD). Men with non-insulin dependent (type 2) diabetes have a two to four-fold greater annual risk of CHD. Women face even higher odds with a three to five-fold risk with type 2 diabetes [1].

Diabetes also magnifies the other risks factors for CHD such as raised cholesterol levels, raised blood pressure and obesity [2]. The INTERHEART study estimated that 15% of heart attacks in Western Europe are due to diagnosed diabetes, so diabetes sufferers were at three times the risk of heart attack [3].

What is diabetes?

Diabetes mellitus is a condition in which the amount of glucose (sugar) in the blood is too high because the body can not use it properly. Glucose comes from the digestion of starchy foods such as bread, rice, potatoes, from sugar and other sweet foods, and from the liver which makes glucose.

Diabetes develops when the body cannot produce insulin. This is a hormone produced by the pancreas that helps the glucose to enter the cells where it is used as fuel by the body.

The two types of diabetes

Type 1 diabetes develops if the body is unable to produce any insulin. This type of diabetes usually appears before the age of 40. It is treated by insulin injections and diet and regular exercise is recommended.

Type 2 diabetes 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 being overweight. This type of diabetes usually appears in people over the age of 40, though in South Asian and African-Caribbean people it can appear after the age of 25. Due to lifestyle and diet changes more children are now being diagnosed with the condition.

Type 2 diabetes is treated with lifestyle changes such as a healthier diet, weight loss and increased physical activity.

Trends in diabetes

More than two million people in the UK have diagnosed diabetes. At least a million more - what charity Diabetes UK calls 'the missing million' - are thought to have diabetes but do not know yet.

Undiagnosed cases

Over 4% of men and 3% of women in England have diagnosed diabetes, according to the Health Survey for England 2003. But the survey also estimates that another 3% of men and 0.7% of women aged 35 and over have undiagnosed diabetes. If this is the case, there are around 582,000 adults with undiagnosed diabetes in the UK making a total of 2.5 million cases in adults in 2006.

Age

Diabetes becomes more common as people get older. Diabetes is increasingly frequently diagnosed up to age 55, with an average age at diagnosis of 52 in people with no family history, or 51 in people with a family history. But it is becoming more prevalent in children and teenagers.

There is increasing concern about the number of children with type 2 diabetes. This has risen tenfold in the past five years, according to Bristol University research published in 2006. A record 100 new cases in children under age-16 were diagnosed in the UK between 2004 and 2005. This study used data from GPs surgeries but the Royal College of Pediatricians and Child Health believe this may be the tip of the iceberg and there are many cases that we are unaware of. A further 60,000 children are thought to be suffering from weight-related metabolic syndrome - a combination of conditions including high blood pressure and raised cholesterol - which is thought to precede type 2 diabetes.

Sex

Men and women are on average, equally likely to be diagnosed with diabetes. However, women with diabetes are more likely to die prematurely. This is because diabetes seems to remove the natural protection against heart disease and stroke that women without diabetes have before the menopause.

Overweight and obesity

A key factor in the rise in diabetes is the fact that as a nation we are increasingly overweight and are less active - factors that increase the risk of developing diabetes. In particular, central body fat - being 'apple shaped' - is strongly linked to insulin resistance, where the body produces but is unable to use insulin properly.

Family history

Diabetes - especially type 2 - tends to run in families. One study showed that in 25 to 65 year olds newly diagnosed with type 2 diabetes, almost half (41%) had a close relative with diabetes.

Ethnicity

Diabetes is three to five times more common among people of African-Caribbean and Asian origin living in the UK. In these groups it tends to develop at a younger age and may be due to different underlying mechanisms, according to Diabetes UK.

References

Morbidity and mortality in the Framingham population. Sixteen year follow up. Diabetes 1974 23:105-111.

Coronary heart disease statistics 2005. British Heart Foundation. Section 12.

INTERHEART Study Investigations 2004. Effect of potentially modifiable risk factors associated with myocardial infarction in 52 countries. The Lancet 364: 937-952.

Health Survey for England 2003. The Stationery Office, London.