Metformin Hydrochloride and Ritonavir in Treating Patients With Relapsed or Refractory Multiple Myeloma or Chronic Lymphocytic Leukemia

Inclusion Criteria: * All subjects must have the ability to understand and the willingness to sign a written informed consent * Life expectancy of \> 3 months * Eastern Cooperative Oncology Group (ECOG) performance status of 0-2 FOR PATIENTS WITH MULTIPLE MYELOMA (MM): * Diagnosis of multiple myeloma * Patients with MM must have measurable disease, defined as one or more of the following: * Serum M-protein \>= 0.5 g/dL * Urine M-protein \>= 200 mg/24 hr * Serum immunoglobulin free light chain (FLC) \>= 100 mg/L (10 mg/dL) and abnormal serum immunoglobulin kappa to lambda FLC ratio * IgA patients must have serum quantitative immunoglobulin \>= 750 mg/dL * Patients with oligosecretory or non-secretory disease must have a documented abnormal free light chain ratio (normal value 0.26 to 1.65) or a value beyond the laboratory calculation range * Disease must be refractory or relapsed after \>= 3 prior regimens (induction therapy and stem cell transplant +/- maintenance will be considered as one regimen) FOR PATIENTS WITH CHRONIC LYMPHOCYTIC LEUKEMIA (CLL): * Diagnosis of CLL without the following: Richter's transformation, prolymphocytic leukemia (PLL), small lymphocytic lymphoma (SLL) * Measurable disease, defined as one or more of the following: * Lymphocytosis \>= 5000 in peripheral blood * Measurable lymph nodes \> 1.5 cm on palpation and/or computed tomography (CT) scan * Organomegaly by physical exam and/or CT scan * Active disease per Internation…