The present invention pertains to the field of manufacture of diagnostic test elements. Specifically, the invention relates to a diagnostic test element for determining an analyte comprised in a body fluid sample, said test element comprising at least one test field with at least one detection layer and at least one separation layer, wherein said at least one separation layer comprises dispersed SiO2 in an amount of about 1.0 to 1.6 g/m2. The invention also relates to a coating composition being capable of forming a separation layer on a diagnostic test element of the present invention described above. Moreover, provided is a method for the manufacture of the diagnostic test element as well as the use of the diagnostic test element for determining the amount of an analyte, preferably, glucose, in a sample of a subject.