I would hazard an educated guess that with such conflicting reports, any effect one way or the other is probably marginal at best. After all, metformin, which is the number one first line drug for type 2 diabetes, only has an effect at maximum dosage of around 1-2 mmol.
However, if you are on warfarin and you have had a gastric bleed, it is REALLY important that you continue to take it, at least until your doctor tells you otherwise. You will come to harm a lot quicker from an uncontrolled gastric bleed than you will from slightly raised blood sugars.