A Study Evaluating the Safety of Inavolisib and Fulvestrant With or Without Palbociclib in Participants With Advanced Breast Cancer (ABC) and Type 2 Diabetes

Inclusion Criteria: * Type 2 diabetes with laboratory fasting blood glucose \< 185 milligrams per deciliter (mg/dL) and HbA1c \<= 8% on any stable anti-hyperglycemic regimen excluding insulin short-term insulin dosing * Eligible for triplet of inavolisib, fulvestrant and palbociclib: no prior systemic therapy for locally advanced unresectable or metastatic disease * Confirmed diagnosis of HR+/HER2- breast cancer * Confirmation of biomarker eligibility (detection of specified mutation(s) of PIK3CA via specified test) * Measurable disease per Response Evaluation Criteria in Solid Tumors, Version 1.1 (RECIST v1.1) * Eastern Cooperative Oncology Group (ECOG) Performance Status of 0-1 * Adequate hematologic and organ function within 14 days prior to initiation of study treatment Exclusion Criteria: * Pregnant or breastfeeding, or intention of becoming pregnant during the study or within the time frame in which contraception is required * Metaplastic breast cancer * Any history of Type 1 diabetes * Severe hyper- or hypoglycemia event within 6 months of initiation of study treatment * Any history of leptomeningeal disease or carcinomatous meningitis * Known and untreated, or active central nervous system (CNS) metastases Participants with a history of treated CNS metastases are eligible * Active inflammatory or conditions in either eye or history of idiopathic or autoimmune-associated uveitis in either eye * Symptomatic active lung disease * History of active bowel inflammation or active inflammatory bowel disease