There's another aspect to this which hasn't been raised.
Suppose the lecturer knew you were diabetic, but still gave you a sweet. Now technically you are (I assume) an adult BUT if anything had gone wrong with your bg levels, then some people would have sued the college because you were given a sugary item by someone who "should have known better". Believe me, I saw this happen over someone who was certainly over 18, but had some problems getting in to college and ended up with a lower class of degree that perhaps their basic IQ would have suggested. The parents sued the college for failing to look after their child properly, under "duty of care" regs because their child would have done better if the college had checked properly as to whether the student was depressed (medical problem - problem college needs to take into account) and not just idle (character flaw - not the college's fault). I'm not identifying student, college or outcome for obvious reasons, but it did happen. After that all lecturers etc were warned to read the several hundred pages which affected "duties to students" in the college handbook. :crazy:
If the college lawyers had seen a lecturer giving sugary treats to a known diabetic they would have hit the roof.
This is stupid, but it's the way the rules work - and there are now people out there who will sue. A greedy solicitor could say that giving sugary treats to anyone is a breach of the duty of care, because they might be diabetic and the lecturer wouldn't know. Or obese - and they're making a serious medical problem worse. And, of course, giving a student a drink should also be a no-no - alcohol abuse being a problem. Incidentally, I was told years ago by someone who'd done a first-aid course, that she could not give anyone a paracetamol any more because she now knew that some people had a bad reaction to paracetamol.
Now, as others have pointed out, you could get the lecturer carpeted for "outing" you as a diabetic and you could complain that they were insufficiently respectful of your right to determine for yourself what you could or could not eat. The only safe course for that lecturer was not to have offered anything to eat or drink to any student in any context, thereby avoiding all the legal minefields. A formal complaint should cause the college management to issue a general directive to all lecturers to that effect. :!: