Addition of 2.5 % alginate to CM reduced peak glucose concentrations , at 30min , by an average of 6 % and 13 % compared with 1.25 % alginate CM ( 95 % confidence intervals ( CIs ) : 0.02-1 .08 ; P = 0.037 ) and CM alone ( 95 % CIs : 0.49-1 .55 ; P = 0.000 ) respectively .