I survived through GD in my 1st Pg (3 months of diet) and due to previous history they did an early test on me on 2nd one and I flunked again. This time almost whole PG in GD.
However I am still trying to control on diet and thankfully did not had to move on to insulin.
My OB had told that its not about eating more carbs/sweets during PG that causes GD, its your body's tendency. When the Placenta grows it puts pressure on your pancreas and they might not be able to take the stress and produce lesser than required amount of insulin. The 1/3 Hr test is foolproof so even if u don't crave for sweets u might still be diagnosed with GD. And due to this body tendency having a GD 2nd time is very likely.
Its not easy to deal with GD but I didn't wanted to take meds so followed my diet chart strictly.
There are lot of options but you have to always read through the lables, choose wisely and be extra cautious while eating out.
I hope u don't have to go through this. Good Luck !!!