Persons developing type 2 diabetes mellitus (T2DM) will typically first have a condition called pre-diabetes. Lifestyle is a major factor that determines whether pre-diabetes becomes full T2DM. Lifestyle includes dietary habits and physical activity. Many people develop T2DM because of poor dietary habits and a sedentary lifestyle. Moreover, eating a high-fat, high-sugar diet can damage the blood vessels and increase the risk of strokes and heart attacks. A person's diet may produce substances in the blood that can interfere with the production of insulin in the pancreas. Sometimes, these changes in the insulin producing cells are serious and can eventually interfere with how the cells in the body use blood sugar, which causes T2DM. Techniques are available to measure circulating substances in the blood of persons with pre-diabetes that may be associated with the development of T2DM. Laboratory research has shown that almonds contain high levels of important compounds that may influence the onset of heart disease and T2DM. A meal plan that includes almonds daily will be given to half of the study participants and the other participants will be given a meal plan that is "nut-free". Because of the potential to delay the onset of heart disease and T2DM in some persons with pre-diabetes, this 16-week study will collect and analyze blood samples for changes that may make the person with pre-diabetes more likely to develop heart disease and T2DM. Blood samples will be collected at weeks 0, 8 and 16 to measure compounds that may be influenced by consuming almonds daily. This study will also attempt to understand other possible causes of heart disease and T2DM in persons with pre-diabetes; particularly those that might be related to body weight and body composition. Body composition techniques using very small amounts of electrical current are available to study body fat. Body weight, waist and hip measurements, blood pressure and body composition testing will be performed at the start of the study and every 4 weeks during the study. Lastly, these other possible causes of heart disease and T2DM will be investigated to look at relationships with the substances in the blood.