diabetic since 6 weeks got to know only at 16 weeks!! plzz help!!!!

Hi.. i am new to this app and a FTM..!due date is nov 22
 I really want to know if anyone has had gestationaldiabetes  from early on in pregnancy
It seems i have had high sugar levels of 140 after 2 hrs of food since 6 weeks but till 15weeks i wasnt aware about it. I tried to cut out processed juices and other things but even thn it is 141 (2 hrs) and 118 during fasting. Iwas  overwieght bfr pregnancy and also have daibetes in my family history.  I am only 23 yrs old though. 
I would like to know if it will cause any defects or problem in my baby as i hv not treated it fr such a long time. 
Plz someone can tell me it is not at all a problem.
Also at my 13 week scan my baby measured a week ahead. Is this bcz of daibeties!