Hi A.,
While I don't know anything specific about gestational diabetes, I was surprised to read that your doctors recommended Splenda. All artificial sweeteners are chemicals and therefore, produce side effects. NutraSweet and Equal are the worst. The chemicals in them are neurotoxins and they turn into formaldehyde in your body (yes, the same thing used to preserve corpses). There is concern about exposure to these chemicals for children in-utero and after birth. Splenda (sucralose) was introduced after the first two, but now research is coming out on it too. I have attached two links you may want to take a look at.
Yes, you have to cut down on real sugar too. But it doesn't have to be replaced with chemicals. I'm not trying to worry you and I’m sure your doctors will say it’s safe, but given that you are pregnant, I just didn't feel right not passing this info along. My view is, why take the chance? I just think it’s very unfair what limited information we are given about what we put in our bodies. You may want to check into some organic stores. They still have sweet items; they just aren’t sweetened with this stuff.
www.sweetpoison.com
http://www.issplendasafe.com/top7reasons.html
Also, if you are concerned about your thyroid, there is a fantastic endocrinologist in Aurora, CO. He is always named a "Top Doctor" and he's great with diabetes and thyroid conditions. I was told mine was fine too and in fact, it was not. His name is Dr. Robert Rees-Jones. Phone: ###-###-####.
http://www.thyroid-info.com/topdrs/colorado.htm
I have attached a link from Dr. Steven Hotze of the Hotze Health & Wellness Clinic in TX. He also talks about artificial sweeteners in his book, but I didn’t see a link to it on the website. He is a doctor and is just as opposed to them (including Splenda). Anyway, I attached his link because he offers a lot of information about thyroid conditions as well as a “test yourself” quiz.
http://www.hotzehwc.com/ebookwomen/
Best of luck & health!