In prediabetes, blood glucose levels are near but not quite at the level that defines diabetes.

Up to six million Canadians have prediabetes that increases their risk of developing Type 2 diabetes and its complications, the Canadian Diabetes Association said Thursday in releasing new guidelines for doctors.

The guidelines stress the importance of identifying those who are at high risk for developing Type 2 diabetes, given its links to heart disease and premature death from heart attacks.

"Research has shown that long-term damage to the body, especially the heart and circulatory system, may already be occurring before a diabetes diagnosis," said Ellen Malcolmson, president and CEO of the association.

"The good news is that for those at risk of Type 2 diabetes, a diagnosis may be prevented if the warning signs are identified early."

Prediabetes refers to impaired glucose tolerance — blood glucose levels that are near but not quite at the level that defines diabetes.

If left untreated, about one quarter of people with prediabetes will go on to have diabetes within three to five years, according to the U.S. Centers for Disease Control.

People with prediabetes need to make lifestyle changes and may need to start taking medications to prevent the onset of diabetes, said Dr. Gillian Booth, methods chair of the committee that prepared the updated guidelines.

Studies have shown that moderate weight loss and regular exercise can delay the onset of Type 2 diabetes by up to 58 per cent.

The 2008 guidelines include revised recommendations for caring for people living with diabetes, as well preventative steps.

More than 2.4 million Canadians have full-blown diabetes, and up to 80 per cent of them will die from heart disease, the association said. Canadians adults with diabetes are twice as likely to die prematurely compared to people without the disease.

For people with diabetes, the guidelines recommend:

• Achieving tight control of blood pressure and cholesterol to reduce complications of heart disease and stroke.
• Improving self-management by increasing physical activity including both aerobic and resistance exercises, along with better nutrition and weight control.
• Reducing saturated fat to no more than seven per cent of daily energy and keeping trans fat intake to a minimum.

Diabetes is a contributing factor in the deaths of approximately 45,000 Canadians each year. Diabetes and its complications cost the Canadian health-care system an estimated $13.2 billion a year, according to the association.