when did patient 52736 get a insulin prescription for the last time in the first hospital visit?
select prescriptions.startdate from prescriptions where prescriptions.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 52736 and admissions.dischtime is not null order by admissions.admittime asc limit 1 ) and prescriptions.drug = 'insulin' order by prescriptions.startdate desc limit 1