The purpose of this study is to evaluate the longitudinal test performance of an array of conventional biomarkers of glycemia, including Hemoglobin A1c (HbA1c), and novel metabolomic biomarkers for identifying progression of glucose tolerance (normal to prediabetes or prediabetes to diabetes) in an overweight and obese pediatric cohort.

Inclusion Criteria:

• Groups 1 and 2 (overweight and obese groups):
• Age 8-17 years for the visits #1 and #2, individuals can be as old as 22 years for follow-up visits #3 and 4
• Overweight or obese, as defined by a BMI ≥ 85th% & <95th% or BMI ≥ 95th%, respectively by age and sex, and for those 16 years and older, BMI ≥25 and <30 and BMI ≥30
• For Group 2 only: previously completed visits 1-2 in 2007-2013 and formally agreed to be re-contacted for study purposes
• Group 3 (Normal weight controls):
• Age 8-17 years
• Healthy weight, as defined by a BMI ≥ 5th percentile & < 85th percentile, respectively by age and sex

Exclusion Criteria:

• Previous diagnosis of type 1 diabetes
• Use of concurrent medications known to affect glucose metabolism (metformin, oral steroids, sulfonylureas, insulin)
• Verbal report of Pregnancy

The study population will consist of normal weight, overweight or obese individuals aged 8 to 17 years at visits #1 and #2, and can be as old as 22 years for follow-up visits #3 and #4. Participants will be recruited from a variety of sites including University Michigan clinical sites, non-University of Michigan clinical sites, schools in the local area, and the University Michigan medical school campus. Participants from Group 2 (visits #3-4) completed visits #1-2 in 2007-2013 and formally agreed to be re-contacted for study purposes.