.
If you found out she has gestational diabetes from anyone else but her, and that she's having a hard time, let it be. If she told you herself in an honest moment of comfort, tell her "I'm so sorry. That sucks." And let her vent. The last thing she wants is for anyone to make a big deal about it, solve her problems, or choose her diet.
Bring in donuts again. Seriously. She's an adult and can choose to eat them.
Bring in a more health conscious option. Once again, she can choose to eat it or not.
You're trying to find an option when most likely you shouldn't know about her personal health issues in the first place. Unless you have a very close relationship that you aren't letting us know about, you shouldn't be trying to figure out something to give her to make her feel better. She could very easily feel ostracized for her pregnancy in the first place. Employers arent super cool with pregnancies, let alone pregnancies that are in any magnitude more difficult.
What makes will make her feel better is a coworker that respects her space and private health matters. Don't treat her as special. Treat her as human.
Is she a tea-drinker? Maybe a bag of some really nice tea from a proper tea shop, herbal or otherwise. My experience is that tea drinkers really appreciate a nice artisan-style brew. It's an understated but thoughtful gesture.
When my wife is in a bad mood I try handing her random objects like a stick from outside. [Wife] you can't be mad, you now have an anti-grumpy stick
*I swear this actually works. We are a strange couple
Maybe a new journal and pen? A coffee or tea? A gift card to treat herself?
Some people don’t want gifts like that, and I’d say respect their wishes. It might make the situation worse otherwise.
Maybe just play it as “I’m running out for a coffee. Let me get you one too.”
I think flowers are over looked too often. It doesn't have to be a romantic gesture! There's plenty of arrangements that just say thinking of you. Go with something small, even from a grocery store. Flowers will put a smile on their face.
Write a note to let that person know how valuable and wonderful a person that they are. Using specific examples is good. This isn't the time for vague platitudes. I would tie any gift in with how much they have done for others, and how deserving they are.
Seconding the Lego suggestion. There's some really nice fairly cheap sets of flowers, succulents, and city postcards.
We buy people Lego flowers instead of real flowers these days. For something that dies super fast, flowers are too damned expensive.
