Chromium Effects on Insulin and Vascular Function in People at Risk for Diabetes

Inclusion Criteria: * Adults * 18 years of age or older * Identified to have impaired glucose tolerance (IGT), impaired fasting glucose (IFG), or insulin resistance. According to the 1999 World Health Organization (WHO) report, IGT is diagnosed if the following two criteria are met: 1) Plasma glucose two hours after consuming 75g glucose (OGTT) is at least 7.8 mmol/l (140 mg/dl) but below 11.1 mmol/l (200 mg/dl) and 2) Fasting plasma glucose level is less than 7.0 mmol/l (126 mg/dl). IFG is diagnosed by a fasting plasma glucose concentration of 5.6 mmol/l (100 mg dl/l) or greater, but less than 7.0 mmol/l (126 mg dl/l). NCEP ATP III guidelines define 5 components of insulin resistance. At least 3 of the 5 criteria are required for the diagnosis. These components are: Abdominal obesity determined by waist circumference \>102cm(\>40in) in men or \>88cm(\>35in) in women; triglyceride level ≥150mg/dL; HDL-C \<40mg/dL in men or \<50mg/dL in women; blood pressure ≥ 130/≥85mm Hg; and fasting glucose ≥ 100mg/dL. -Connecticut residents willing to travel to Griffin Hospital in Derby, CT Exclusion Criteria: * Known diabetes (Fasting Plasma Glucose \> 126 mg/dl; 2-hour 75-g OGTT plasma glucose \> 200 mg/dl; * Diabetes diagnosed by a physician and confirmed by other clinical data); * Self-reported hospitalization for treatment of heart disease in past 6 months; * Impaired renal function as measured by labwork at initial screening (serum creatinine greater than 2.0 Serum creatinine and urine albumin excretion will be tested every six months throughout the study). Significant changes from baseline or to outside of threshold will be reported to the DSMB for appropriate action, including removal from the study. * Self-reported pancreatitis. In the instance that potential subjects report that they are unsure whether they have been diagnosed with this condition, a primary medical doctor's note will be obtained confirming non-diagnosis before inclusion in the study. * Self-reported recent or significant abdominal surgery; * Self-reported pregnancy and/or intention become pregnancy during the study. Women of child-bearing age will consent to pregnancy testing at baseline, and will agree to avoiding pregnancy by reliable means throughout the duration of the study. * Self-reported polycystic ovarian syndrome or irregular menses will be excluded from the study. (In the future, people with self-reported polycystic ovarian syndrome or irregular menses may be allowed in the study, however, because their conditions have the potential of affecting the outcome of BARS testing (a secondary outcome), they will be treated as a subset of the population during data analysis).