Diabetes mellitus is a common chronic disease. The prevalence of diabetes in the U.S., particularly type 2 diabetes, is increasing. Its complications impose a large burden on a high proportion of people with diabetes. This burden is particularly high in certain minority populations and in older adults. While it is generally accepted that people who have diabetes and poor glycemic control are more susceptible to periodontal disease, recent evidence suggests that there is a bi-directional adverse interrelationship between diabetes mellitus and periodontal disease whereby periodontal infection may also adversely affect glycemic control. However, to date this evidence remains equivocal and population-based evidence is very limited. Further, there is a paucity of information on the bi-directional relationship between diabetes and periodontal disease in older adults. This proposed study will use two rich datasets, The National Health And Nutrition Examination Survey (NHANES) and the VA Normative Aging Study and VA Dental Longitudinal Study (VANAS/DLS) to address important gaps in the knowledge about interrelationships between periodontal disease and diabetes. The aims of this study for analysis of NHANES data will be to determine if periodontal disease is associated with the prevalence of systemic complications of diabetes mellitus (cardiovascular disease, cerebrovascular disease, retinopathy and visual impairment, nephropathy, and peripheral arterial disease) in U.S. adults with type 2 diabetes. The aims of analysis of the VANAS/DLS data will be to determine, in older adult males, if diabetes is a risk factor for periodontal disease incidence, severity, and progression;if periodontal disease increases the risk for impaired glucose tolerance and poorer glycemic control;and if periodontal disease is associated with both the prevalence and incidence of diabetes complications and diabetes-related medical care utilization. These aims will be accomplished by testing a series of detailed hypotheses using rigorous multivariable statistical analyses appropriate for the complex sample design of NHANES data and the longitudinal nature of the VANAS/DLS data. The results of this study will provide important, population-based evidence to determine if periodontal disease is independently associated with a higher prevalence of complications of diabetes mellitus (NHANES). Also, this proposed study will provide the opportunity, in the VANAS/DLS data analyses, to evaluate the bidirectional relationships between diabetes and periodontal diseases as well as the relationship between periodontal disease and the prevalence and incidence of poorer glycemic control, diabetes complications and related medical procedures in a study group of older adult male veterans. Project Narrative: This study will use very large datasets to study how gum disease and diabetes affect each other in people with type 2 diabetes. It will also study if gum disease has an effect on the other medical problems that people with diabetes often have, such as problems with the eyes, kidneys, heart and blood vessels, stroke, and nerves. About 21 million Americans have diabetes and over 90% have type 2 diabetes. Many have a lot of suffering and high health care costs, as well as time lost from work. This study will help determine if it is important to consider gum disease as a condition that makes diabetes worse.