All depends on if you are a foreigner or a local. If a foreigner, unless you are making more than 7K/mo, you will need a degree as a diploma will not justify getting an employment pass (with the exception of maybe an S pass if you have enough experience).
If you are a local, a degree holder will still command more starting salary than a diploma holder regardless of grades as the local employer wants to see the sheepskin and normally not too interested in the transcripts unless the job entails a good command of written English.
At the end of the day, the degree / diploma only get you to the interview. It's up to you to convince the jury that you can do the job and after getting the job, it's up to you to show the employer that they haven't made a mistake. Show them well, and normally you will be well compensated, or a competitor will poach you!
Sluff off and you will be history and so will your earning capacity, regardless of your academic background.