I'm not a doctor, and I don't know much about hypertension, and
thus I cannot recommend much...
What I can say is, you could start on some weights training too.
Start light, but do the compound exercises (deadlifts, bench press,
squats). It would be good to begin on an empty barbell. If you are
at a ClubFitt gym, you could always ask any instructor to teach you
(for free
). This could be in
addition to your cycling (do continue with it). Afterall, more
muscles = more calories burned during resting periods 
Regarding diabetes, perhaps it would be beneficial for you to watch
your diet, to focus more on low glycemic index food such that there
isn't any insulin spike, but rather, a slower and gradual release
of carbs into your blood stream. Food with low GI includes oats
(instant one I not sure), brown rice, multi-grain bread from
Gardenia (they claim low GI), wholemeal bread, etc.