CDL licenses (truck drivers, etc...) require fairly stringent certification in order to obtain one. They're easy to do once you know what the qualifications are, but they have some rules that are sometimes arbitrary. Diabetics pose an interesting problem with them since you have to simultaneously have controlled blood sugars but can't be on anything injectable (insulin) to get them under control. I had a trucker come in once for his yearly certification. This required me to check his average blood sugar, called a hemoglobin A1C. Normal is 7% or below, his was 14% (WAY out of control). In order for him to be certified I had to have him at the 7% mark, something that would take about 2-3 years of stringent control to get him to that level. I looked at his med list and noticed that he had been on long-acting insulin (and somehow still got his license). I asked him if he'd been taking it and he replied, "No, I quit taking that because I knew I couldn't be on it and drive a big rig."