A test element configured for determining first and second analytes, comprising: a first coenzyme-dependent enzyme or a substrate for the first enzyme; a second coenzyme-dependent enzyme or a substrate for the second enzyme; and a coenzyme selected from the group consisting of thio-NAD, thio-NADP, and a compound according to formula: in which A = adenine or an analog thereof, wherein said analogue of adenine is selected from C8-substituted adenine; N6-substituted adenine; 8-aza adenine; and 7-deaza adenine, wherein said 7-deaza adenine is optionally substituted in the 7 position with halogen, C1-C6-alkinyl, C1-C6-alkenyl or C1-C6-alkyl; T = in each case independently denotes O or S, U = in each case independently denotes OH, SH, BH 3 -, or BCNH 2 -, V = in each case independently denotes OH or a phosphate group, W = COOR, CON 2, COR, or CSN 2 in which R in each case independently denotes H or C 1 -C 2 -alkyl, X 1, X 2 = in each case independently denote O, CH 2, CHCH 3, C(CH 3) 2, NH, or NCH 3, Y = NH, S, O, or CH 2, Z = a residue comprising a cyclic group with 5 C atoms which optionally contains a heteroatom selected from O, S and N and optionally one or more substituents, and a residue CR4 2 wherein CR4 2 is bound to the cyclic group and to X 2, and where R4 = in each case independently denotes H, F, Cl, or CH 3, provided that Z and the pyridine residue are not linked by a glycosidic bond, or a salt or optionally a reduced form thereof, wherein the first analyte is hydroxybutyrate and the first enzyme is a hydroxybutyrate dehydrogenase and wherein the second analyte is glucose and the second enzyme is a glucose dehydrogenase or a glucose oxidase. a first coenzyme-dependent enzyme or a substrate for the first enzyme; a second coenzyme-dependent enzyme or a substrate for the second enzyme; and a coenzyme selected from the group consisting of thio-NAD, thio-NADP, and a compound according to formula: in which A = adenine or an analog thereof, wherein said analogue of adenine is selected from C8-substituted adenine; N6-substituted adenine; 8-aza adenine; and 7-deaza adenine, wherein said 7-deaza adenine is optionally substituted in the 7 position with halogen, C1-C6-alkinyl, C1-C6-alkenyl or C1-C6-alkyl; T = in each case independently denotes O or S, U = in each case independently denotes OH, SH, BH 3 -, or BCNH 2 -, V = in each case independently denotes OH or a phosphate group, W = COOR, CON 2, COR, or CSN 2 in which R in each case independently denotes H or C 1 -C 2 -alkyl, X 1, X 2 = in each case independently denote O, CH 2, CHCH 3, C(CH 3) 2, NH, or NCH 3, Y = NH, S, O, or CH 2, Z = a residue comprising a cyclic group with 5 C atoms which optionally contains a heteroatom selected from O, S and N and optionally one or more substituents, and a residue CR4 2 wherein CR4 2 is bound to the cyclic group and to X 2, and where R4 = in each case independently denotes H, F, Cl, or CH 3, provided that Z and the pyridine residue are not linked by a glycosidic bond, or a salt or optionally a reduced form thereof, wherein the first analyte is hydroxybutyrate and the first enzyme is a hydroxybutyrate dehydrogenase and wherein the second analyte is glucose and the second enzyme is a glucose dehydrogenase or a glucose oxidase. A = adenine or an analog thereof, wherein said analogue of adenine is selected from C8-substituted adenine; N6-substituted adenine; 8-aza adenine; and 7-deaza adenine, wherein said 7-deaza adenine is optionally substituted in the 7 position with halogen, C1-C6-alkinyl, C1-C6-alkenyl or C1-C6-alkyl; T = in each case independently denotes O or S, U = in each case independently denotes OH, SH, BH 3 -, or BCNH 2 -, V = in each case independently denotes OH or a phosphate group, W = COOR, CON 2, COR, or CSN 2 in which R in each case independently denotes H or C 1 -C 2 -alkyl, X 1, X 2 = in each case independently denote O, CH 2, CHCH 3, C(CH 3) 2, NH, or NCH 3, Y = NH, S, O, or CH 2, Z = a residue comprising a cyclic group with 5 C atoms which optionally contains a heteroatom selected from O, S and N and optionally one or more substituents, and a residue CR4 2 wherein CR4 2 is bound to the cyclic group and to X 2, and where R4 = in each case independently denotes H, F, Cl, or CH 3, provided that Z and the pyridine residue are not linked by a glycosidic bond, or a salt or optionally a reduced form thereof, wherein the first analyte is hydroxybutyrate and the first enzyme is a hydroxybutyrate dehydrogenase and wherein the second analyte is glucose and the second enzyme is a glucose dehydrogenase or a glucose oxidase.