Metformin and Nightly Fasting in Women With Early Breast Cancer

Inclusion Criteria: * Women with histologically confirmed luminal (ER+ve and/or progesterone \[PgR\]+ve \>= 1%) operable IBC (cT1-2, cN0-1, Mx) candidate to elective surgery and not to neo-adjuvant treatment. Women with larger tumors who refuse neo-adjuvant chemotherapy before surgery can also be eligible. Luminal HER2+ve (cT1, cN0) IBC and DCIS are also eligible * Age \>= 18 years * Eastern Cooperative Oncology Group (ECOG) performance status =\< 1 (Karnofsky \>= 70%) * Leukocytes \>= 3,000/microliter * Absolute neutrophil count \>= 1,500/microliter * Platelets \>= 100,000/microliter * Aspartate aminotransferase (AST) (serum glutamic-oxaloacetic transaminase \[SGOT\])/alanine aminotransferase (ALT) (serum glutamate pyruvate transaminase \[SGPT\]) =\< 1.5 x institutional upper limit of normal * Creatinine within normal institutional limits * Creatinine clearance estimated with Cockcroft-Gault formula \> 45 mL/min * Female participants of child-bearing potential must agree to use contraception such as barrier method of birth control or abstinence, prior to study entry and for the duration of study participation. Should a woman become pregnant or suspect she is pregnant while participating in this study, she has to inform her study physician immediately. The effects of metformin hydrochloride extended release on the developing human fetus at the recommended therapeutic dose are unknown * Ability to understand and the willingness to sign a written informed consent document Exc…