I let my instructors know. I just finished my first semester of college and most my instruction thanked me for letting them know because if something goes wrong say your having a low blood sugar and you pass out or something it's important for them to know you have diabetes and they asked me for permission to go into my purse and get me something to eat if that ever where to happen. I think it's important I always let them know.
I think it is time to bring this discussion to life. I just read an email about a professor upholding a "no eating in class" rule on a hypo diabetic who was undeclared. Student fought the academic sanction and lost because of the university's rule on declaring being required for accommodation.
I am just a retired T2 prof.
As the new school year begins I am going to refresh one of my older posts in this section to bring it back to life.
As a retired T2 college professor on a pump, a point of law is shared with all college professors in the USA, whether they remember it or not. The USA - Americans with Disabilities Act educational component says students must declare their disability to the school's disability support services or not be eligible for accommodation. For example, if a college has a rule about "no eating in a classroom" and a diabetic starts hypo in the middle of a quiz and needs to eat, if they are not on the school's disability list, then they must leave the quiz to treat their "undeclared" hypo. If they have declared to the school's disability office, then they can eat at their seat and continue on the quiz. This is NOT FAIR in my eyes but it is the way many schools look at disabilities - declared = real, undeclared = does not exist.
So, my two cents worth is - if you are a student, declare your diabetes to your disability office and review the accommodations your are seeking like: eat in class when no eating rules apply, testing BG during class - step into hall or perform at seat, have pump that beeps and not be "penalized" for not silencing a communications device, and similar events.
Bottom line, always discuss your needs with the school's disability support office so you have as much protection to defend from college faculty who may be so far into their subject matter they forget how to be human and compassionate. You can hold your trump card (a letter from the school disability support office stating you are entitled to accommodation for hypos etc) until you need to play it.
There are old diabetics and Bold diabetics. I have not seen old, bold diabetics.
For me, it depends on the size of the class. If the class is really big (over 100) than I don't because chances are they'll just out you in the lump of students who have health issues. If the class is smaller than 100, I do tell the professor because it's usually more noticeable if you're absent or not feeling well because of diabetes. And it's usually more noticeable if you're eating or drinking or doing anything related to diabetes.
One of the few side effects of the spread of diabetes is that more and more people know about it and what it entails. For example, several of my professors understood more than I expected about me potentially needing to test/eat food/put numbers into my pump/etc.