instruction: what is patient 71559's monthly minimum glucose level until 03/2103?
response: SELECT MIN(labevents.valuenum) FROM labevents WHERE labevents.hadm_id IN (SELECT admissions.hadm_id FROM admissions WHERE admissions.subject_id = 71559) AND labevents.itemid IN (SELECT d_labitems.itemid FROM d_labitems WHERE d_labitems.label = 'glucose') AND STRFTIME('%y-%m', labevents.charttime) <= '2103-03' GROUP BY STRFTIME('%y-%m', labevents.charttime)