People with high fasting glucose can develop type 2 diabetes with the passage of time. This study is being done to determine the effect of a novel medication in people with this elevated fasting glucose. Sitagliptin is a substance that raises levels of a hormone normally found in the blood. This hormone, called glucagon-like peptide-1 (GLP-1), is normally released by the intestine in response to the presence of food. This hormone acts like a messenger between the intestine and the pancreas to raise insulin levels, and therefore, lower blood sugars. Sitagliptin is effective in people with diabetes, however, this study is being done to determine if Sitagliptin is effective in people with high fasting glucose who do not yet have diabetes.

• Drug: Sitagliptin
• Other: Placebo

• Active Comparator: People with impaired fasting glucose treated with sitagliptin 100mg once daily.
• Placebo Comparator: People with impaired fasting glucose treated with placebo once daily.

Twenty four participants aged 35 to 70 years with impaired fasting glucose (100mg/dl-125 mg/dl) will be studied. We will screen up to twice that number i.e. 48 which will allow for dropouts or screen failures. Individuals with a body mass index less than 19 or greater than 40 kg/m2, or a total weight > 130kg, will be excluded from study to avoid potential confounding effects that may result from extreme leanness or obesity. Subjects greater than age 35 years of age will be eligible for study. Subjects less than 35 years will not be studied in order to minimize the possibility of studying subjects with type 1 diabetes. Subjects must be in good health as determined by past medical history and a physical examination inclusive vital signs, electrocardiogram, and laboratory tests at the time of screening. Healthy subjects will mean that the participant has no history of a) significant nephropathy, (i.e., plasma creatinine > 1.4 mg/dl in women and 1.5 mg/dl in men, and/or proteinuria); b) clinically significant atherosclerotic vascular disease (e.g., history of MI or angina); c) a known systemic illness. Patients on diuretics or thyroid hormone therapy must be on a stable dose (at least 3 months prior to screening) and the maintenance dose may not be adjusted during the study