Is ingesting too much sugar directly responsible for diabetes mellitus type 2?

Indirectly: There is the failure of the pancrease (pancrelipase) to produce sufficient insulin, also involves the ability of the cell to "use" the insulin, the amount of gycogen converted to sugar by the liver, as well as the absorption of the sugar by digestive system. However, the more sugar you intake the more stress you place on these organs to do their work. Is the fire worse when you add gasoline ?

No: Diabetes mellitus type 2 is because of the body unable to metabolize sugar. In a normal person meaning if the pancreas functioning optimally, excess sugar ingestion should not rise blood sugar levels.