This study includes a longitudinal mixed methods study of 360 YYA with diabetes in SC, CO, and WA conducted with SFS 1 participants. SFS 2 will have two parts: (1) an intense, longitudinal study consisting of two 14-day assessment periods spaced 9 months apart which will include CGM, EMA, accelerometry, and surveys in all participants (the EMA study); and (2) a concurrent events qualitative study with a subset of participants (30 T1D, 15 T2D) who will complete 13 one-on-one, semi-structured interviews throughout the 9-month assessment period (the qualitative study).

This study will help determine the safety and effectiveness of BIIB122, compared to placebo (an inactive substance), in people with early-stage Parkinson's disease. The use of BIIB122 in this study is investigational. "Investigational" means that the study drug is currently being tested and is not approved by the U.S. Food and Drug Administration (FDA) or any other health authorities around the world for treating people with PD. The study is expected to last a minimum of 1 year to a maximum of 3 years. You may or may not receive direct medical benefit from participating in this study. Your condition may get better, worse, or stay the same. The information obtained from this study, however, could help other patients with your disease in the future.