It is not easy to see directly how Miracle-Mineral-Supplement could help diabetes, except that we don't know why it is that the body stops producing enough insulin. I believe that pathogens are at the root of more health problems than we give them credit for, probably aided by genetic factors, environmental pollutants, poor diet and lack of exercise. Miracle-Mineral-Supplement does seem to have a good effect on our pathogen load or on our body's ability to handle it. If pathogens are promoting the degeneration of our insulin-production mechanism, which is a possibility, then Miracle-Mineral-Supplement could help reverse that.
I have only seen anecdotal evidence in a video about Jim Humble's work that a woman in Mexico who had diabetes found after taking MMS that she didn't need so much (or any?) insulin any more. That's not really convincing evidence, but if people with diabetes who take MMS could report in about their experience we would know more.