People who might have prediabetes or unrecognized diabetes will be screened for these problems at an outpatient visit. For screening, they will take a sugary drink containing 50 grams of glucose, and have a blood sample one hour later. The blood sample will be tested for glucose and A1c (a measure of blood glucose over the previous two months). They will also fill out questionnaires that ask about their health history and how they would feel about exercising and trying to lose weight if they are found to have prediabetes or diabetes. At a subsequent visit, they will have an oral glucose tolerance test (OGTT) - a blood sample, then a sugary drink containing 75 grams of glucose, and a repeat blood sample 2 hours later. We will evaluate the costs of finding out if people have prediabetes or diabetes. For people who are found to have these problems, we will also evaluate how well their doctors treat these problems.