Diabetes doubles risk of heart attack and strokes

Diabetes is now estimated to be responsible for 1 in every 10 deaths from cardiovascular disease, or about 325,000 cardiovascular deaths per year in all industrialised countries put together.

The results come from an analysis of 700,000 people by an international consortium led by Dr Nadeem Sarwar and Professor John Danesh of the University of Cambridge. The report is published in this week's Lancet and will be presented at the American Diabetes Association's 70th Scientific Sessions in Orlando, Florida. The findings underscore the need to prevent diabetes in the face of increasing rates worldwide.

Cardiovascular disease is the leading cause of death globally, responsible for about 17 million deaths every year. Diabetes has long been recognised as a major risk factor for cardiovascular disease, but the extent of its effect on different blood vessel diseases has been debated. It has also been uncertain how much of the effect of diabetes on blood vessel diseases is due to higher levels of blood fats, blood pressure, and obesity.

The new study involved a combined analysis of individual records on 700,000 people, each of whom was monitored for about a decade in 102 surveys conducted in 25 countries.

The findings show that having diabetes approximately doubles the risk of a wide range of blood vessel diseases. Perhaps surprisingly, however, only a small part of the effects of diabetes was explained by blood fats, blood pressure, and obesity. This finding suggests that diabetes may exert its harmful effects via additional routes.

According to Dr Sarwar: "Our findings highlight the need for better prevention of diabetes coupled with greater investigation of the mechanisms by which diabetes increases the risk of cardiovascular disease."

The study also found that in people without diabetes higher-than-average fasting blood glucose levels were only weakly related to subsequent development of heart attack or strokes.

This finding argues against using information on blood glucose levels to help identify people at higher risk of heart attack or stroke. Dr Sarwar added: "Information on age, sex, smoking habits, blood pressure and blood fats is routinely collected to assess risk of developing cardiovascular disease. Our findings indicate that adding information on fasting blood glucose levels in people without diabetes does not provide significant extra help in assessing cardiovascular risk."