I very much doubt all that Dr Clark is saying about diabetes, it does not go along with my research & understanding about the cause which shows why the pancreas tail is usually unable to regenerate in type 1's. It's possible but difficult and it is unlikely to spontaneously heal without work on the descending colon.
What type of diabetic are you? I have been type 1 for most of my life. The cause of my diabetes shows in my left iris, including a genetic abnormality of my pancreas tail and why I became diabetic which shows in my descending colon. I suggest that you take a look because the iris can show quite a bit of information as to the causes of illness and what needs to be done to correct it. An iris chart by Dr Bernard Jensen will be helpful, google images have some large Dr Jensen colour iris charts.
There are many natural substances and foods which can lower blood Sugar levels but be very careful if you are taking medication! Green Tea can lower BS and can also stimulate body fat reduction as I have found myself.