If the time-difference between DateTimePicker A and B will always be
smaller than
24 hours then this will do:
Dim diffMinutes As Int32 = (dtpB.TimeOfDay - dtpA.TimeOfDay).TotalMinutes
if diffMinutes < 0 then
diffMinutes += 24 * 60
end if
If the time-difference can be greater than or equal to 24 hours you will have to include the date into the calculation and then it's simply
(dtpB.Value - dtpA.Value).TotalMinutes