News & Research

    Mayo Clinic Rochester, Rochester, Minnesota

The independent contribution of trends in obesity and diabetes to recent slowing of declines in CAD prevalence: A population-based study of non-elderly decedents who died from non-natural causes 1981-2009

General Research Subject: Type 2 Diabetes

Focus: Epidemiology

Type of Grant: Clinical Translational Research

Project Start Date: January 1, 2010

Project End Date: June 30, 2013

Research Description

Dramatic declines in heart disease morbidity/mortality since the mid-1960s are attributed to successful programs of smoking reduction and blood-pressure control and considered one of the century's top public-health successes. By contrast, the proportions of Americans who are obese and/or are affected by diabetes are increasing rapidly, and efforts toward prevention have been generally unsuccessful. The epidemics of obesity and diabetes raise concerns that the steady declines in heart disease morbidity/mortality may soon end, and will likely reverse.

However, a shortage of available evidence to support these predictions fuels arguments that such concerns are exaggerated, thus contributing to complacency and further reducing the likelihood that prevention programs will succeed. Findings from Olmsted County, MN, by members of our group suggest that continued declines in heart attacks and deaths mask alarming trends in sub-clinical disease, especially among younger individuals. We examined extent of coronary artery disease (CAD) at autopsy among non-elderly Olmsted County residents who died from accident/suicide/homicide 1981-2004. CAD at autopsy declined over the full time period, but further investigation revealed the declines ended in 1995, and we saw suggestive evidence of an increase after 2000. We propose to update and expand our previous study to 1) test if increases in CAD have continued, 2) test if trends in obesity/diabetes contributed to these changes, and 3) assess whether trends in CAD risk factors and history observed for decedents apply to their non-deceased peers. Such findings would help reduce complacency, enhance chances for successful prevention, and improve the health of subsequent generations.

Researcher Profile

What area of diabetes research does your project cover? What role will this particular project play in preventing, treating and/or curing diabetes?

This study investigates temporal trends in macrovascular complications of diabetes. Specifically, we will examine the extent to which marked increases in obesity and diabetes within the population have contributed to increases in the prevalence of coronary atherosclerosis, a precursor of heart disease morbidity and mortality.

A growing number of authors suggest that concerns over the epidemics of obesity and diabetes may be overblown. Their arguments are based on a lack of evidence for any slowing of declines in the rate of hospitalizations for myocardial infarction (MI) and in the rate of deaths due to heart disease. We believe such arguments fail to take into account the time lag between the onset of obesity and diabetes (for which increases over time have been greatest among younger individuals) and the adverse complications of MI and death (for which the occurrence is greatest among elderly individuals). We believe that, for the present, evidence of the impact of the epidemics of obesity and diabetes on heart disease morbidity must focus on trends in subclinical disease.

If a person with diabetes were to ask you how your project will help them in the future, how would you respond?

The interest in and funding for diabetes prevention and treatment is related to demonstrating the adverse consequences that diabetes has for affected individuals, their families, and the population at large. If recent arguments that 'trends in heart disease morbidity and mortality are unaffected by recent epidemics of obesity and diabetes' go untested and unchallenged, the topics of diabetes prevention and treatment may not receive the attention they deserve.

Why is it important for you, personally, to become involved in diabetes research? What role will this award play in your research efforts?

As an anthropologist/epidemiologist, I am interested in understanding how trends in age-related chronic disease incidence, prevalence, and survival are associated with dramatic declines in deaths due to heart disease over the past half century. One possibility is that declines in mortality resulted from improved prevention and later age at onset of chronic disabling disease. Another possibility is that declines in mortality resulted from improved survival among persons already affected by chronic disabling disease. These two possibilities have opposite consequences for the overall burden of illness within the population and future demands for care. My colleagues and I examined these issues in my first project as a principal investigator after graduate school (funded in 1991by NIH). We took advantage of opportunities afforded with the unique longitudinal population-based records-linkage resources of the Rochester Epidemiology Project, and we used diabetes as a model.

Type 2 diabetes is a relatively common condition among older adults; it is accompanied by marked morbidity and disability, premature mortality, and high costs. Thus it provided an excellent model to help distinguish between these two possibilities. At the time of this first project (nearly 2 decades ago), we and others were beginning to document marked increases in the proportions of the population affected by obesity and diabetes within the population. We showed that age-adjusted prevalence of diabetes rose 65% for men and 37% for women between 1970 and 1990. We showed that this increase was due to a greater frequency of new cases of diabetes within the population rather than an increase in the relative survival for persons with diabetes. Our findings in this and many subsequent studies by our group emphasize the need for heightened surveillance and intervention to reduce the burden of illness from adult-onset diabetes mellitus in the population. The present ADA award will help us directly test the hypothesis that increasing rates of obesity have contributed to continuing increases in diabetes and that both are contributing to increases in subclinical atherosclerosis.

In what direction do you see the future of diabetes research going?

I see the future of diabetes research going in at least two directions: first, increasing our understanding of the different mechanisms underlying the development of diabetes and how these different mechanisms respond best to treatment (i.e., individualized medicine) and second, where best to intervene along the trajectory of obesity, diabetes and diabetes complications to afford improved independent life expectancy and quality of life and reductions in cost (i.e., the science of health-care-delivery).