Two anatomy scans?

So next week I’ll be 15 weeks and I have to see a specialist and get a “specialized anatomy scan” because I’m a type 2 diabetic. Thing is, I’ve been diabetic since before I had children, my oldest is 2.5 and I have the same OB for this pregnancy. I keep my diabetes in check with diet, exercise, and metformin. They didn’t do any of this with my first pregnancy, I had a fairly standard pregnancy, baby measured two days ahead and I was told that’s normal. Baby is measuring two days ahead again and I’ve been told everything looks normal this time too, yet I’m getting a super early anatomy scan AND another at 20 weeks. Has anyone else dealt with this? I have access to my medical records and there’s nothing to suggest my doctor is keeping anything from me (which is what several relatives hypothesized 🙄) and to clarify, yes they are calling this an anatomy scan and told me that’s what it is even though it’s so early. Just another edit regarding why I didn’t ask why they were doing this: I was simply told it’s because I’m diabetic, and when I press further that’s really all I get. I’ve had no luck asking my OB and I’m supposed to see a specialist but I don’t have the specialist’s number and the hospital at which the specialist is supposed to be at says they don’t have a specialist so everything’s kind of up in the air currently.