The massive rise in type 2 diabetes in recent years, the serious health risks associated with the condition, and the fact that several risk factors for the disease can be modified, have created great interest in whether diabetes can be prevented.

Most programs aiming to prevent diabetes have focused on high-risk groups, particularly people whose blood glucose is already moderately raised. Recent studies have shown that lifestyle advice can be extremely effective at reducing diabetes risk in these groups.

The largest of these studies was the Diabetes Prevention Program (DPP) carried out in the USA. This study involved 3,234 overweight people with impaired glucose tolerance (IGT). IGT is an intermediate state between normal blood glucose control and type 2 diabetes, sometimes referred to as 'pre-diabetes'. IGT carries a high risk of progressing to type 2 diabetes. In addition, almost half the DPP participants were from an ethnic group at increased risk of diabetes.

The DPP subjects were divided into three groups, who received:

• general lifestyle advice once a year, plus metformin (a drug that lowers blood sugar), or
• general lifestyle advice once a year, plus a placebo (dummy pill), or
• intensive lifestyle advice (16 sessions over 24 weeks) encouraging weight loss and increased physical activity.

The subjects were followed up for an average of 2.8 years. Compared to the placebo group, the incidence of diabetes was 58% lower in the group that had received intensive lifestyle advice, and 31% lower in the group who had received metformin. This was an extremely encouraging result.

Although frequent lifestyle advice, given by a trained health professional, reduces the number of people at high risk who go on to develop diabetes, even the most effective lifestyle program will not work for everyone. As diabetes carries such serious health risks, there is a growing feeling that people at high risk of diabetes who do not respond to lifestyle advice should be given drugs to reduce their risk. A number of large clinical trials are in progress to investigate whether drugs that improve insulin secretion, or improve the body's sensitivity to insulin, can prevent - or at least delay - the development of diabetes in people at high risk. It is believed that delaying diabetes will also delay or prevent diseases related to diabetes, such as cardiovascular diseases and kidney damage.

Additional Information from Novartis Pharmaceuticals

A large diabetes prevention trial, called NAVIGATOR, is in progress. It involves 7,500 people with IGT and at least one other cardiovascular risk factor (e.g. high blood pressure, raised cholesterol) or disease (e.g. angina, previous heart attack). If you are resident in the USA and might be interested in taking part in this trial, click here for more information from Novartis Pharmaceuticals, the trial sponsors.