Change from Gliclazide to Gliclazide MR - now have massive spikes never seen so high .

After a recent Heart bypass and the subsequent meds for that , my Glucose levels increased, so I was for the first time also prescribed Gliclazide along with my usual Sukarto SR (Metforman).
MY gliclazide was initially prescribed 40 Mg twice a day , 0800 hrs & 1800hrs whilst in the hospital but this dose was having no effect , so it was increased to 80 Mg twice a day that did have a significant effect , but still not quite good enough (the Hospital diabetes team said it would take time to settle to an appropriate dosage .) and it s possibly giving me stomach issues .
So a recent visit to my GP, and explained this , I have since been put on Gliclazide MR , once a day 120 Mg , but since then my Glucose readings are massive going from an average of 6-7 mmol/L now up to 12 and spiking 14.9 + mmol/l . My diet has not changed in the last 7 days since being changed on my meds, the med details are that this dose is less in mg but is equivalent to my previous dosage and is better for my "insides".

I am of course going to give it a few more weeks to see if it settles down , but given the very high figures, I wont wait too long .

So has anyone recently been changed from standard GLIC to the Modified Release and had any similar experiences ?