The Civil Aviation Authority (CAA) has said qualified pilots and air traffic controllers with diabetes treated with insulin and other medications can carry out full operational duties, including flying commercial aircraft.
The change, made in August, was significant because since 2002 pilots with diabetes have been able to fly recreationally only.
However, licensed pilots and air traffic controllers who have diabetes will need to demonstrate good overall control of their condition before gaining medical qualifications to fly.
Dr Stuart Mitchell, head of the CAA's medical section, said: "With the appropriate level of monitoring to ensure safety standards, it is right that these experienced individuals can contribute their skills and knowledge in their chosen field."
Barbara Young, chief executive of Diabetes UK, said: "The CAA has acknowledged that advances in the management of diabetes, along with the appropriate level of testing and monitoring, ensure that safety standards are maintained.
"The decision will be of huge benefit to the many qualified pilots and air traffic controllers who have not been able to fully participate in their chosen field."
The CAA is set to issue more detailed guidance to pilots and air traffic controllers explaining the new procedures, including details of operational restrictions and in-flight testing regimes.