Yes it is vital to have good control before conception because it is during the first 12 weeks that the baby is developing & that is when abnormalities can occur. You should also take a higher amount of folic acid than non-diabetic women (in the UK it is 5mg) because diabetics have a higher chance of having a baby with neural tube defects. Preferably the folic acid should be started 3 months before you conceive.
It is a bit of a rollercoaster with blood sugars when you are pregnant. Many women find their blood sugars increase before they find out they are pregnant (mine didn't though!) & it is generally around the 8 week gestation stage when you really need to watch out for the horrible lows. They can come on fast!! And you can lose your hypo awareness too. As you reach the 3rd trimester that is when many women start to become insulin resistant - I'm 28 1/2 weeks & I think I am on the verge of hitting insulin resistance (boo!).
It's all good though - you just need to test loads & change your I:C ratios accordingly.
