1. Has a current diagnosis of familial or acquired partial lipodystrophy or autoimmune (Type 1) diabetes mellitus
2. Any malignancy, eg, lymphoma, within the past 1 year, prior to screening visit, as described in the protocol
3. eGFR of <30 mL/min/1.73 m2 based on Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) creatinine or Schwartz equation, as applicable, at screening. Assessment can be repeated once
4. History of heart failure hospitalization, diagnosis of a myocardial infarction, stroke, clinically significant arrhythmia, as described in the protocol
5. Treatment with over-the-counter or prescription medications with the intention of weight loss within 3 months prior to the screening visit

For Part A only:

1. Treatment with metreleptin within 3 months of the screening visit
2. Addition or discontinuation of prescription medications or over-the-counter supplements for diabetes and/or dyslipidemia within 3 months prior to the start of the screening period, or changes in the use of these medications, as described in the protocol
3. Significant changes to lifestyle and diet, as described in the protocol
4. Current chronic treatment with high-dose corticosteroids, defined as use of higher than physiologic doses, as described in the protocol

NOTE: Other protocol defined inclusion/exclusion criteria apply.