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