I think that most people could appreciate the care and effort from somebody else wishing the best for them, but I personally (and many of the folks from /r/diabetes_t1) wouldn’t appreciate somebody suggesting how they should improve on managing their new disease. Everyone goes through the adjustment process differently and that honestly could be more of a setback.

But I will say I was misdiagnosed as t2 for several months until I visited with an endocrinologist who ordered the right tests to differentiate between the two (c Peptide to determine insulin production and an antibody test to determine autoimmunity).

Now I don’t know what your relationship with your coworker is, but I wouldn’t say anything unless they asked for any input. I understand the frustration of seeing somebody not doing well in managing their issues but this is really a “they need to help themselves before you can help them”.