Boston, MA - Higher-than-optimum blood glucose levels are responsible for 21% of deaths from ischemic heart disease and 13% of deaths from stroke worldwide, which, when added to the deaths from diabetes itself, puts this condition in the top five causes of worldwide mortality, accounting for 3.16 million deaths a year, a new study shows [1].

The study, published in November 11, 2006 issue of the Lancet, was conducted by a group led by Dr Goodarz Danaei (Harvard School of Public Health, Boston, MA).

They explain that quantifying the health effects of raised blood glucose levels is complicated for many reasons. These include the fact that mortality rates based on deaths assigned directly to diabetes underestimate the total burden of the condition, as they do not take into account the many cardiovascular deaths caused by diabetes or blood glucose levels that are raised but well below the conventional threshold values that define diabetes.

The researchers thus assembled a database of comparable estimates of blood glucose distribution by age, sex, and country. They collated data in 52 countries from individual-level records in population health surveys, systematic reviews, and data provided by investigators. They used this, together with data on the continuous association between blood glucose and cardiovascular mortality risk, to estimate mortality from ischemic heart disease and stroke attributable to higher-than-optimum blood glucose concentrations in different world regions, by age and sex.

Results showed that in addition to 959 000 deaths directly assigned to diabetes, 1 490 000 deaths from ischemic heart disease and 709 000 from stroke were attributable to high blood glucose, accounting for 21% and 13% of all deaths from these conditions. Of these 2.2 million cardiovascular deaths, 1.8 million (84%) were in low- and middle-income countries.

"Our results show that one in five deaths from ischemic heart disease and one in eight from stroke worldwide are attributable to higher-than-optimum blood glucose, and more than three million people are dying each year as a result of raised glucose levels. This figure is comparable to deaths from smoking (4.8 million), high cholesterol (3.9 million), and obesity (2.4 million)," the authors say. They conclude: "Cardiovascular risk and diabetes management and control programs need to be more closely integrated rather than being in different spheres."

In an accompanying editorial, Drs Mauricio Avendano and JP Mackenbach (University Medical Centre, Rotterdam, the Netherlands) point out that this study shows that mortality attributable to higher-than-optimum blood glucose levels is about three times higher than that attributable to diabetes, emphasizing the fact that the effect of raised blood glucose levels has been grossly underestimated [2].

They suggest that the focus on diabetes should be switched to a "continuous exposure perspective." They point out that as there is a positive continuous association between blood glucose and cardiovascular risk that extends well below the usual fasting glucose level for diabetes or related disorders, this gives great potential for prevention below these thresholds and that this continuous association places particular focus on population-based prevention approaches. "In other words, we need interventions aimed at shifting the distribution of glucose concentrations leftward in the entire population."

They say that the first step toward this goal should be to make lifestyle changes, noting that lifestyle interventions have been shown to prevent progression to diabetes by as much as 58% and delay diabetes by 11 years in high-risk groups such as individuals with impaired glucose tolerance. But as 84% of cardiovascular mortality attributable to raised glucose levels is in low-income and middle-income countries, these interventions need to be cost-effective.

They admit that what these population interventions should look like is still uncertain and that more research is needed, but they do say: "Upstream approaches need to be developed to address the underlying environmental determinants of healthy behavior." And they give examples that include designing pedestrian-friendly environments and improving access to healthy food choices. "Changing the physical environment is a major public-health challenge, endorsed by WHO in its 'Making the healthy choice the easy choice' slogan," the editorialists write. "Such an effort needs to involve several sectors of society: from governments responsible for dictating policies on agriculture and transportation to the retail and food industries responsible for ensuring availability of healthy products," they conclude.