Hello. Your loss of interest and other symptoms makes the diagnosis of depression
very clear. Also the medical disorders you have mentioned makes one prone to it as well as a stressor like this in your age group. I m sure you have been treated for depression by your doctor but you are not getting benefitted . There can be many reasons for it.
Firstly as you have mention your blood sugar is still raised , it means your diabetes
is not in control and despite treatment you are not able to get full benefit of it.
Secondly your son despite being in a college may not be performing as per your expectations and you are in a persistent stressor and thus not getting benefitted
Thirdly your medication need a change as they are not helping you as you want
Fourthly you may be in need of psychotherapy
along with medication to make you learn to cope with these stressors and which help you to come out of it.
According to me you need to evaluate which problem is most likely and get a intervention done according to it.