The simplest way to think about the effect of strong steroids is to look at the dawn phenomenon that we all know and love...
So - that is caused by the release of Cortisol at the start of the day - ok - so far so non-controversial. But - what is Cortsisol, why, it's a naturally produced cortico-steroid, which is why when you are injected with a large dose of external cortico-steroids (all steroids which are not anabolic steroids are cortico-steroids) it has exactly the same effect as Cortisol, and your blood glucose shoots up.
As your blood glucose goes up - like any time this happens - your blood insulin will go up (with the usual caveats about meds and a functioning pancreas) - and when insulin goes up, ketone production will drop.
However - I'm not trying to contradict
@Kiwigal - be aware of the symptoms of DKA and do measure your ketones if you can - Gliclazide will affect insulin so it's a possibility, but DKA is a state of out-of-control ketone production alongside high blood glucose because you either have no insulin, or you are so insulin resistant that it's having no effect. If your recent control was good, and you are going through a short-term situation because of steroids - you are probably doing the only thing you can, getting a lot of rest and recovering to the point that you can stop the steroids - and regroup.
