I just went for mine today (27 weeks) but I could've gone anytime between 26 & 28 weeks. If you have concerns, I'd let you Dr know as I know they will test early if you have certain risk factors.
I did mine at 25w. I was high risk for GD so did an early test around 16w too. If you are worried or have reason to be worried, ask to be tested early too. You can test more than once throughout your pregnancy.
After 2 m/cs, dx October 2008 with hetero factor v leiden & mthfr & low progesterone; third time was the charm - BFP 3/19/09 on first cycle of clomid.
If you have known risk factors (ie. family history, obesity, etc etc), they will often test you earlier.
Otherwise, it is typically done between 24-28 weeks depending on the practice. Testing early won't catch it in many women. You need to be far enough along to develop it as it is due to hormones the placenta is producing that is creating the insulin resistance.
Re: When do they test for GD?
If you have known risk factors (ie. family history, obesity, etc etc), they will often test you earlier.
Otherwise, it is typically done between 24-28 weeks depending on the practice. Testing early won't catch it in many women. You need to be far enough along to develop it as it is due to hormones the placenta is producing that is creating the insulin resistance.