Diabetes Epidemiology: Guiding Clinical and Public Health Practice
The Kelly West Award Lecture, 2006
- William H. Herman, MD, MPH
- From the University of Michigan Health System, Ann Arbor, Michigan
- Address correspondence and reprint requests to William H. Herman, MD, MPH, Stefan S. Fajans/GlaxoSmithKline Professor of Diabetes, Professor of Internal Medicine and Epidemiology, Director, Michigan Diabetes Research and Training Center, University of Michigan Health System, 3920 Taubman Center, Ann Arbor, MI 48109-0354. E-mail:
- DCCT, Diabetes Control and Complications Trial
- DPP, Diabetes Prevention Program
- IGT, impaired glucose tolerance
- TRIAD, Translating Research Into Action for Diabetes
- QALY, quality-adjusted life-year
Epidemiology provides a scientific basis for clinical and public health practice. Indeed, epidemiology can be used to guide how we define, diagnose, and screen for diabetes, to describe the present and future burden of diabetes, and to highlight opportunities for intervention.
What is diabetes?
Diabetes is a group of disorders characterized by high glucose levels that cause unique eye, kidney, and nerve complications and an increased risk for cardiovascular disease. A number of approaches have been used to diagnose diabetes. Some have been based on statistical approaches to defining abnormal or high glucose levels and others on the risk of complications. In populations with a low prevalence of diabetes, glucose levels are normally distributed and diabetes may be defined as glucose levels greater than the mean glucose level plus 2 SDs (Fig. 1A). In the 1950s, Stefan Fajans and Jerome Conn studied large groups of healthy lean individuals without family histories of diabetes, administered oral glucose loads, and measured glucose levels at time intervals following the glucose loads. They observed normal distributions of glucose levels 60, 90, and 120 min after the glucose load and defined abnormal glucose tolerance based on this simple approach (1). In populations with a high prevalence of diabetes, there is a bimodal distribution of glucose levels and diabetes may be defined as glucose levels greater than the antimode (Fig. 1B). Bimodal glucose distributions were first observed among Pima Indians (2), and analyses based on this finding were subsequently used by the National Diabetes Data Group (3) and the American Diabetes Association Expert Committee (4) to establish the fasting and 2-h post–glucose load glucose criteria for diabetes.
Another approach to diagnosing diabetes looks at the association between glucose level and complications and defines diabetes as glucose levels above the threshold associated with complications (Fig. 1C). The problem with this …