That sounds strange. Someone who is marginally Type II diabetic would normally get by on Metformin, without even needing extreme dietary changes (although dietary changes would be beneficial, and an extreme calorie restricted diet under medical supervision might even have reversed the disease- although that is a more recent discovery).
If the doctors decided you needed more insulin later, it might be because your disease had worsened to that point. Or they might be honouring your decision to use insulin, or they might have misjudged the situation, assuming that you required insulin, because you were taking it.
I am certainly not convinced that Fung is right in any area where he disagrees with mainstream medical science.