Evaluation of the Clinical Spectrum of Diabetes and Obesity in Youth and Adults

* INCLUSION CRITERIA: In order to be eligible to participate in this study, an individual must meet all of the following criteria: 1. Age 8 years to 65 years 2. Meet at least one of the following: a. Overweight/Obesity: i. For participants under 18 years of age: BMI \>= 85th percentile for age and sex ii. For participants \>= 18 years of age: BMI \>= 25 kg/m\^2 (\>=23 kg/m\^2 for self-reported Asian race/ethnicity) b. Suspected or evidence of hyperglycemia: i. Diagnosis of prediabetes or diabetes in medical history or by participant/guardian/Legally Authorized Representative (LAR) report, OR ii. Fasting blood glucose \>= 100 mg/dL in medical record, OR iii. Postprandial blood sugar \>= 140 mg/dL in medical record, OR iv. Hemoglobin A1c \>= 5.7% in medical record EXCLUSION CRITERIA: An individual who meets any of the following criteria will be excluded from participation in this study: 1. History of significant medical illnesses that the investigators feel may interfere with potential evaluations, i.e. individuals who are critically ill, unstable, or with severe organ failure that may affect/limit the endocrine evaluation and place unsustainable demands on Clinical Center or NIDDK resources. 2. History of any medical, psychiatric, or social conditions which, in the opinion of the investigators, would make participation in this protocol not in the best interest of the participant. 3. Inability or unwillingness of participant, parent/guardian, or LAR to provide informed consent.