instruction: what is the first value of the bedside glucose of patient 002-58884 a month before?
response: SELECT lab.labresult FROM lab WHERE lab.patientunitstayid IN (SELECT patient.patientunitstayid FROM patient WHERE patient.patienthealthsystemstayid IN (SELECT patient.patienthealthsystemstayid FROM patient WHERE patient.uniquepid = '002-58884')) AND lab.labname = 'bedside glucose' AND DATETIME(lab.labresulttime, 'start of month') = DATETIME(CURRENT_TIME(), 'start of month', '-1 month') ORDER BY lab.labresulttime LIMIT 1