I used to be able to drive a 7.5 tonne truck until the DVLA and government medical officials changed the rules since that rubbish truck in scotland drove into and killed people as the driver had a heart attack at the wheel and in a nutshell you have to have excellent health to drive a truck 7.5 tonnes and above , as an insulin depandant diabetic i applied for my C1 licence (7.5 tonne) back again , went through all the blood monitoring for many months, dvla sent me to an independant diabetic consultant who examined my monitor sent the readings off to DVLA then got a letter off DVLA who took my car licence and therefor my livelyhood off me until i could proove i was able to control my diabetes. i had 2 hypos in the 3 months i monitored my blood for, 3 times a day for 3 months and did not miss one test.
Good luck in trying to convince the government medical board and DVLA that your able to handle your diabetes and a truck, it took me 6 months to convince them i was stable and then i got my car licence back, my advice...dont even bother.