AutoCAD .NET :: How To Check And Manage Unit To Insert Block Reference

I have a VBA code for check and choose unit but how i can in .NET ?

Unite = ThisDrawing.GetVariable("INSUNITS") Select Case Unite Case 4: Unite = 10 'mm Case 5: Unite = 1 'cm Case 6: Unite = 0.01 'm Case Else: Unite = 1 End Select

db.UnitMode is always = 0

i have try this :

Dim BlocT As BlockTable Dim tr As Transaction = db.TransactionManager.StartTransaction BlocT = tr.GetObject(db.BlockTableId, OpenMode.ForRead) Dim Bloc As BlockTableRecord Bloc = tr.GetObject(BlocT(BlockTableRecord.ModelSpace), OpenMode.ForRead) Dim lay As Layout = tr.GetObject(Bloc.LayoutId, OpenMode.ForRead) tr.Commit() tr.Dispose()
 but bloc.units dont egal the unit command in autocad.

I can use  :

Dim obj As Object = Application.GetSystemVariable("INSUNITS")

but i want a proper solution with .net.