what was the last value of a glucose laboratory testing of patient 11823?
select labevents.valuenum from labevents where labevents.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 11823 ) and labevents.itemid in ( select d_labitems.itemid from d_labitems where d_labitems.label = 'glucose' ) order by labevents.charttime desc limit 1