White healthy male adults ( n = 15 ) and white , well-defined male and female prediabetic adults ( n = 15 ) received test drinks randomly on 3 different occasions at least 2 d apart which contained 50 g of maltodextrin19 ( MD19 ) alone or in combination with 50 g of whey protein isolate ( WPI ) or 50 g of sodium caseinate ( SC ) .