AFAIK you do NOT have to inform DVLA if you are taking Victoza or Byetta, nor do you have to tell them if you are taking these drugs alongside Gliclazide and/or Metformin. You must tell them if you are on Insulin, and also if (on whatever medication you are) you suffer hypos that require you to receive help from a third party. You can get full details of all this from the DVLA website.
I am on Byetta, and the information sheet mentions pancreatitis as a possible (but rare) side effect. There is no mention of pancreatic or kidney cancer. Before you would be prescribed Byetta (or Victoza) you will need blood tests to ensure your liver and kidney functions are good enough to enable your body to metabolise the drug, and if not you will not be given it as this would increase the risk of pancreatitis etc.. I was hoping to be given Victoza (single daily injection) but my kidney function was not good enough for this, so I am on Byetta (two injections daily) instead.
Neither Victoza nor Byetta cause hypos in themselves, only in combination with other drugs such a gliclazide and insulin, when hypos "can occur very commonly" in the words of the Byetta leaflet. If you have good hypo awareness there is no need for DVLA to be informed if you are on Byetta with Gliclazide and/or Metformin. You do, however, need to inform your insurance company if you are diabetic, but they should NOT increaseyour premium as a result.
Hope this makes the situation clearer.