Family history of diabetes as a potential public health tool

Abstract

Given the substantial morbidity and mortality associated with type 2 diabetes, it is important that public health seek ways to delay or prevent the onset of this condition. Risk factors for type 2 diabetes are well established and include underlying genetic susceptibility. Despite this knowledge, as well as significant advances in understanding the human genome, the prevalence of type 2 diabetes continues to rise at an alarming rate. Because type 2 diabetes is a complex condition involving a combination of genetic and environmental factors, DNA testing for susceptibility genes is not yet warranted. However, because family history reflects genetic susceptibility in addition to other factors, it may be a useful public health tool for disease prevention. When evaluating family history as a public health tool, several important issues need to be considered, including the analytic and clinical validity and the clinical utility of using family history as a screening tool. These issues as well as a review of the epidemiologic evidence evaluating family history as a risk factor will be reviewed.

Overall, a family history approach appears to be a promising new public health tool to fight the growing epidemic of diabetes in the United States. Adequate levels of funding to further evaluate this approach and to develop appropriate tools should be made available for research activities focused on this important area.

Introduction

Type 2 diabetes is a significant public health problem, accounting for substantial morbidity and premature mortality in the United States. The estimated annual direct and indirect economic costs of managing type 2 diabetes and its sequelae are $98 billion.1 The prevalence of type 2 diabetes among adults varies by age and ethnicity,2 and it continues to rise at an alarming rate among youth.3 Importantly, the public health burden of type 2 diabetes may be underestimated because approximately 33% to 50% of individuals with type 2 diabetes (about 8 million) remain undiagnosed and untreated.2, 4 Furthermore, it is estimated that diagnosis and treatment may be delayed 4 to 7 years; as a result, many patients with diabetes will already have complications of the disease by the time of clinical diagnosis.5

Risk factors for type 2 diabetes are well established2 and include age, race and ethnicity, obesity, and lack of physical activity. The frequency of diabetes is greater among individuals with hypertension or dyslipidemia and in women with a prior history of gestational diabetes. Evidence for genetic susceptibility to type 2 diabetes is also well established.6, 7, 8, 9, 10 However, the genetics of type 2 diabetes is complex, and it is unlikely that single major genes will account for a substantial proportion of the disease.

The American Diabetes Association (ADA) recently issued a position statement that included a review of four randomized controlled trials,11, 12, 13 which showed that simple lifestyle modifications such as a healthy diet, increased physical activity, or pharmacologic interventions can significantly decrease the incidence of diabetes in high-risk populations.14 Evidence from these studies suggests that preventing or delaying the onset of type 2 diabetes is possible. However, population screening for diabetes, even in high-risk populations, is not currently recommended by the ADA.15 Thus, developing and evaluating strategies to identify at-risk individuals who may benefit from targeted interventions are important and challenging public health responsibilities.

Family history information may serve as a unique and useful tool for public health and preventive medicine.16 Because family history reflects both genetic and environmental factors, it may serve as a better predictor of diabetes risk than either factor alone. If this is the case, family history could then be used to identify individuals at different levels of risk or to influence health promoting behaviors. Further, prevention efforts could be extended to family members who may be at increased risk or who may be influential in helping to modify a relative’s health behavior.

The purposes of this paper are to review the epidemiologic evidence about family history as a risk factor for type 2 diabetes, to assess the analytic and clinical validity and the clinical utility of family history information as a screening tool for type 2 diabetes, to identify gaps in knowledge in these areas, and to illustrate the importance of ethnic and cultural considerations when collecting and using family history information.