Hi, I wasn't diabetic when I had my two kids. However, I am telling you this so you can stop feeling down. They both measured big for dates. My first was born early at 30 weeks and thankfully was 2-3 weeks bigger than he should have been. My second also measured 2 - 3 weeks bigger at around 28 weeks. He was born at 40 weeks and was exactly average length and weight at birth. I think some babies must just grow more quickly than expected. If you have been managing to keep your blood sugars within range you have done really well. and that's all anyone can ask of you. Please don't feel down, it may just be 'one of those things' that happens from time to time. Though I expect other type ones may be able to help you more I thought I would tell you my own experience.