There is definite two fold increase in depression incidence in diabetic patients; this could be either related to metabolic effects of diabetes per-se or the day to day stress. It seems your diabetic control seems satisfactory and I recommend you can take cadflo capsule 20 mg, once daily, at bed time, to start with for 2-3 weeks and depending upon its response you can increase to 1 in morning and 1 at night. I still advice later, some time, you can see a Psychiatrist as well clinical psychologist and get evaluated. I would not recommend any higher doses of the above medication because theoretically they may sometimes worsen diabetic status as per the reports from US.