Chemotherapy and Radiation Therapy With or Without Metformin Hydrochloride in Treating Patients With Stage III Non-small Cell Lung Cancer

Inclusion Criteria: * Pathologically (histologically or cytologically) proven diagnosis of stage IIIA or IIIB non-small cell lung cancer within 84 days of registration; eligible histologies include adenocarcinoma, adenosquamous, large cell carcinoma, squamous carcinoma, non-lobar and non-diffuse bronchoalveolar cell carcinoma or non-small cell lung cancer not otherwise specified) * Patients must have measurable disease * Patients must have unresectable disease, be medically inoperable, or unwilling to undergo surgical management * Appropriate stage for protocol entry, including no distant metastases, based upon the following minimum diagnostic workup: * History/physical examination, including documentation of height, weight, body surface area, and vital signs, within 30 days prior to registration * Computed tomography (CT) with IV contrast or magnetic resonance imaging (MRI) imaging (if CT scan with contrast is medically contraindicated) of the lung and upper abdomen through the adrenal glands, required within 45 days prior to registration (recommended within 30 days prior to registration * MRI of the brain with contrast (or CT with contrast if MRI is medically contraindicated) within 45 days prior to registration; note: the use of intravenous contrast is required for the MRI or CT; an MRI without contrast is only permitted if the patient has a contrast allergy * Whole-body fludeoxyglucose (FDG)-positron emission tomography (PET)/CT required within 45 days prior to …