Is there a better/more concise way to write this sql query?

[Supplement]

Instead of using 'case' as many times as i do?

select
case
when b.patient_id is null then a.dfcode else b.dfcode
end as dfcode,
case
when b.patient_id is null then a.diagcode else b.diagnosis
end as diasgnosis,
case
when b.patient_id is null then a.times_testing else b.times_testing
end as times_testing,
case
when b.patient_id is null then a.on_insulin else b.insulin
end as insulin
from event.dbo.patient_dg() a
left outer join event.dbo.diabetes_rx_tracker b on a.code=b.patient_id and b.image_id='2110180'
where a.code='ADSMANZS01'