a 77-year-old right-handed woman presents with a history of right-side hemiparesis and global aphasia. she has long-standing diabetes, for which she takes metformin; she also has a history of well-controlled hypertension. ct shows large left hemispheric infarction. on examination, she is alert, and you notice that she appears queasy. she has been incontinent of urine since admission. serum analysis shows elevated glucose. glomerular filtration rate shows mild renal insufficiency; dipstick urinalysis is glucose positive, and post-void residual volume is 80 ml.