Gingernut,
Your quote - "
Hypoglycaemia isn't an issue with dietary control and metformin, and I've never known it with sulphonylureas. (eg gliclazide)"
My family is rife with diabetes, my father (Type I), my cousin (Type I), my daughter (Type I), and my wife Type II.
My cousin and my daughter had to quit flying when diagnosed as Type I, top marks to them that they did so responsibly without trying to hide it.
Getting back to your query, my wife with Type II diabetes with dietary control and Metformin prescribed, has some "very near" hypoglycaemic attacks from time to time, particularly if carbohydrate intake has been low. Whilst it should be theoretically impossible for her to suffer a "full blown" hypo, her blood glucose reading at the time has been as low as 2.8 mmol/L (Please convert if you use another system of management). If my father or daughter reached that level, they'd be walking on the ceiling!
My top marks go to the many VERY responsible people in this thread who have accepted their condition, and acted responsibly in withdrawing from flying. It will be my turn one day, genetics say so! (So far so good).
Regards,
Old Smokey