INS and obesity due to melanocortin 4 receptor deficiency: Among the 58 metabolites significantly associated with both BMI and obesity, isoleucine was positively associated with diabetes in the Complex Diseases in the Newfoundland population: Environment and Genetics (CODING), Longitudinal Evaluation in the Arthritis Program: Osteoarthritis Study (LEAP-OA), the Newfoundland Osteoarthritis Study (NFOAS), and the Tasmanian Older Adult Cohort study (TASOAC) (p ≤ 0.04, Tables S1 and S2), and positively associated with glucose, insulin, and HOMA-IR levels in the CODING cohort (p ≤ 0.01, Tables S3 and S4).