A glucose oxidase according to SEQ ID NO: 1, selected from the group consisting of a) a glucose oxidase according to SEQ ID NO: 1, having besides the two amino acid substitutions T30V and I94V, at least one additional amino acid substitution in any of the five positions selected from the group S53; A173; A332; F414; V560 in said SEQ ID NO: 1; or b) a glucose oxidase that exhibits at least 70%, particularly at least 80%, or > 90% amino acid sequence identity to the glucose oxidase according to a) provided that the glucose oxidase of b) is having besides the two amino acid substitutions T30V and I94V, at least one additional amino acid substitution in any of the five positions selected from the group S53; A173; A332; F414; V560 according to SEQ ID NO: 1, and provided that the glucose oxidase according to b) exhibits at least 70%, particularly at least 80%, or > 90% of the enzyme activity of the glucose oxidase according to a), and exhibits at least 70%, particularly at least 80%, or > 90% of the enzyme specificity for glucose of the glucose oxidase according to a), and provided that the glucose oxidase according to b) exhibits at least a 5-fold reduced activity for oxygen as electron acceptor of the glucose oxidase according to SEQ ID NO: 1 or exhibits at least a 1.5-fold increased activity for electron mediators other than oxygen of the glucose oxidase according to SEQ ID NO: 1, or both; or c) an active fragment of a glucose oxidase according to a) or b), provided that in the active fragment according to c) the amino acid substitutions as outlined under a) or b) are preserved when compared to the glucose oxidase according to a) or b), and provided that the glucose oxidase according to c) exhibits at least 70%, particularly at least 80%, or > 90% of the enzyme activity of the glucose oxidase according to a), and exhibits at least 70%, particularly at least 80%, or > 90% of the enzyme specificity for glucose of the glucose oxidase according to a), and provided that the glucose oxidase according to c) exhibits at least a 5-fold reduced activity for oxygen as electron acceptor of the glucose oxidase according to SEQ ID NO: 1 or exhibits at least a 1.5-fold increased activity for electron mediators other than oxygen of the glucose oxidase according to SEQ ID NO: 1, or both, and wherein the amino acids for additional substitution(s) are selected from the group Phe for the position S53; and/or Ile, Thr, Val for the position A173; and/or Ser, Val, Thr for the position A332; and/or Ile, Leu, Met, Val for the position F414; and/or Leu, Pro, Thr, for the position V560. a) a glucose oxidase according to SEQ ID NO: 1, having besides the two amino acid substitutions T30V and I94V, at least one additional amino acid substitution in any of the five positions selected from the group S53; A173; A332; F414; V560 in said SEQ ID NO: 1; or b) a glucose oxidase that exhibits at least 70%, particularly at least 80%, or > 90% amino acid sequence identity to the glucose oxidase according to a) provided that the glucose oxidase of b) is having besides the two amino acid substitutions T30V and I94V, at least one additional amino acid substitution in any of the five positions selected from the group S53; A173; A332; F414; V560 according to SEQ ID NO: 1, and provided that the glucose oxidase according to b) exhibits at least 70%, particularly at least 80%, or > 90% of the enzyme activity of the glucose oxidase according to a), and exhibits at least 70%, particularly at least 80%, or > 90% of the enzyme specificity for glucose of the glucose oxidase according to a), and provided that the glucose oxidase according to b) exhibits at least a 5-fold reduced activity for oxygen as electron acceptor of the glucose oxidase according to SEQ ID NO: 1 or exhibits at least a 1.5-fold increased activity for electron mediators other than oxygen of the glucose oxidase according to SEQ ID NO: 1, or both; or c) an active fragment of a glucose oxidase according to a) or b), provided that in the active fragment according to c) the amino acid substitutions as outlined under a) or b) are preserved when compared to the glucose oxidase according to a) or b), and provided that the glucose oxidase according to c) exhibits at least 70%, particularly at least 80%, or > 90% of the enzyme activity of the glucose oxidase according to a), and exhibits at least 70%, particularly at least 80%, or > 90% of the enzyme specificity for glucose of the glucose oxidase according to a), Phe for the position S53; and/or Ile, Thr, Val for the position A173; and/or Ser, Val, Thr for the position A332; and/or Ile, Leu, Met, Val for the position F414; and/or Leu, Pro, Thr, for the position V560.