Also from the NHS website is this interesting 2014 report on grapefruit juice and diabetes. In the reported study, grapefruit juice was as effective at lowering blood sugar as metformin, a leading drug for type 2 diabetes. However, this report cautions about the results - the study was not carried out on humans, but on non-diabetic mice:

Could grapefruit juice protect against diabetes?

https://www.nhs.uk/news/diabetes/could-grapefruit-juice-prot...