Furthermore , supplementation with anthocyanin lowered fasting plasma glucose ( by 8.5 % ; P < 0.05 ) and homeostasis model assessment for insulin resistance index ( by 13 % ; P < 0.05 ) , and elevated serum adiponectin ( by 23.4 % ; P < 0.01 ) and - hydroxybutyrate ( by 42.4 % ; P = 0.01 ) concentrations compared with placebo supplementation .