Abstract: Process for the specific determination of the serum fructosamine content in blood or in samples obtained from blood by reaction with an appropriate color reagent and measurement of the color change thereby brought about, in which before the color reaction sample components with a non-specific reducing action and/or causing turbidity are removed and subsequently the color reagent is added at a pH value of from 10 to 12. The sample components are removed by treatment at approximately neutral pH value with a reagent composition comprising at least one enzymatic oxidation agent, optionally together with peroxidase and/or catalase and/or lipase, as well as with at least one SH group-blocking substance. A kit for the specific determination of the serum fructosamine content in blood or samples obtained from blood, comprises said reagent composition, a rebuffering reagent with a buffer which has an alkaline pH value and a color reagent for the detection of fructosamine.