Diabetes is emerging as a major focus of public health efforts in the United States and worldwide because the burden of the disease is increasing rapidly. The increasing prevalence of diabetes is alarming because of the broad spectrum of acute and long-term complications that typically occur in combination and lead to extensive disability and substantial mortality, while imposing substantial human and economic costs on individuals, families, communities, health care systems, and society. Diabetes management was once considered the domain of the physician–patient relationship, guided by basic science and clinical research. Research focused on the physician–patient relationship is now being complemented with risk reduction media campaigns, health services research, and community-based participatory research. This article summarizes key scientific studies of primary, secondary, and tertiary prevention that provide evidence that diabetes complications can be prevented and controlled. We also discuss how findings from large-scale randomized clinical trails support the critical need for complementary public health approaches to address and eliminate persistent health disparities, using health systems, health communications, and community intervention research and practice.
Type 2 diabetes (hereafter referred to as diabetes) is emerging as a major focus of public health efforts in the United States and worldwide because the burden of the disease is increasing rapidly. In the United States, the prevalence of diagnosed (including gestational) diabetes increased by 61 percent from 1990 to 2001,1 and the prevalence of diagnosed diabetes is projected to increase by 165 percent from 2000 to 2050.2 In 2000, of the estimated 17 million Americans with diabetes, 5.9 million had not been diagnosed.3 Globally, the number of adults with diabetes is projected to increase from 135 million in 1995 to 300 million in 2025, an increase of 122 percent.4 The increasing burden of diabetes in the United States is associated with rapid, parallel increases in the prevalence of major risk factors for type 2 diabetes, including weight gain, physical inactivity, and poor eating habits.1 In the United States the economic costs attributable to diagnosed diabetes, including direct medical and indirect expenditures, were estimated to be $132 billion in 2002.5
The increasing prevalence of diabetes is alarming because of the broad spectrum of acute and long-term complications of the disease. Microvascular damage caused by diabetes makes it the leading cause of blindness and renal failure in adults, whereas macrovascular damage associated with diabetes increases the risk of coronary heart disease, stroke, and peripheral vascular disease 2- to 4-fold.3 In addition, peripheral arterial disease and peripheral neuropathy associated with diabetes make it the leading cause of nontraumatic lower-extremity amputation.3 This wide range of complications, which typically occur in combination, leads to extensive disability and substantial mortality and imposes substantial human and economic costs on individuals, families, communities, and health care systems.
Diabetes mellitus is characterized by high concentrations of blood glucose resulting from defects in insulin production, insulin action, or both.3 The main types of diabetes are type 1, type 2, and gestational. Type 1 diabetes, which accounts for 5 percent to 10 percent of all diagnosed cases, usually develops in children and young adults, who require insulin treatment for survival.3 Type 2 diabetes, which accounts for 90 percent to 95 percent of diagnosed cases, is associated with older age, obesity, family history of diabetes, race or ethnicity, physical inactivity, and other factors, and it is increasingly being diagnosed in children and adolescents.3 Gestational diabetes is diagnosed in some women during pregnancy; women with an affected pregnancy are at increased risk for type 2 diabetes.3 All forms of diabetes require medical treatment or lifestyle modification or both. To prevent long-term complications, treatment includes sustained control of glucose; ongoing care to prevent eye disease, kidney disease, and amputations; and control of cardiovascular disease risk factors such as hypertension, dyslipidemia, and smoking to prevent myocardial infarction and stroke.6
Diabetes management was once considered the domain of the physician–patient relationship, guided by basic science and clinical research and informed by observational studies and later by large, randomized controlled clinical trials. Today, diabetes management incorporates findings from health services and translation research and from systematic reviews. A critical role for public health has emerged with the growing evidence that complications of the disease can be prevented if effective intervention strategies are developed, implemented, and sustained. Federal investment in state diabetes control programs began in 1977, the same year the National Institutes of Health established academic Diabetes Research and Training Centers to accelerate the transfer of clinical research findings into clinical practice. Public health approaches proven to reduce the burden of diabetes involve entire communities and health systems and include state and federal legislation and policies.
To address the enormous and rapidly increasing burden of diabetes, public health interventions can improve diabetes management and prevent complications and, potentially, prevent, or delay the development of type 2 diabetes in persons at high risk. This article summarizes key scientific studies of primary, secondary, and tertiary prevention that form the foundation for the public health response to diabetes in the United States, which will be described in the companion articles and commentaries in this supplement. Because of the substantial and compelling scientific evidence that the complications and disability associated with diabetes can be prevented or delayed, we begin with a review of the literature on secondary and tertiary prevention, highlight translation research efforts, discuss the scientific basis for primary prevention of type 2 diabetes, and conclude by discussing the rationale for public health approaches in diabetes prevention and control.