Here's an interesting (long) interview with ketone researcher, Dr Dominic D'Agostino and at around 1:05:39 he starts talking about a study they're getting ready to publish that shows the BG lowering effects of exogenous ketones - he said they lower BG much more than metformin. Hmnnnnn, I might have to try ordering some from the US. He also thinks they will speed up keto-adaptation.
P.S. I'm not talking about products like "raspberry ketones" that are not ketones at all. I'm talking about products that have recently come on the market like Kegenix, etc. (that use esterified ketones as developed by Dr D'Agostino's lab)