Answers
A1: I've been rated 20% for SC diabetes since 2006, due to Agent Orange. I've never been able to receive an increase. And, as a DAV Service Officer, I can tell you that we haven't seen a rating higher than 20% for diabetes. However, that's not to say, that if you condition has gotten worse and you've been diagnosed as such, by a VA or private doctor and you can provide evidence, that you should try to get an increase.
Also,
1) If you have neuropathy of your feet/hands - this is a secondary to diabetes - should put in a claim (with evidence of cause). If you are approved, you should receive a rating anywhere from 30% - 40%.
2) if you have Erectile Dysfunction (ED), it can be caused by the diabetes medication you're taking. Ask your doctor to confirm this condition and then you can file a claim for ED. This won't get you a rating, but the VA will increase your benefit by approx., $150/month. And, the VA can prescribe Viagra and it can be free if you are 30% or more. (JL) 1/20/19
A2: I have seen many ratings at 40% for DM II. The key is not whether or not you use insulin or how much you use but, to get to 40%, the doctor has to regulate your activities because of your diabetes. i.e. you cannot go into the sun due to the medication you take for DM II, etc. (DS) 1/22/19
A3: Check the 38 CFR. In order to get an increase, you need three things, insulin, restricted diet, and restricted activity. You must have all three. (AP) 2/1/19