Diabetic nephropathy (DN) is a microvascular complication of type 2 diabetes mellitus (T2DM) that develops after years of T2DM and affects approximately one in four diabetic patients. Thioredoxin (TXN), thioredoxin reductase (TXNRD), and thioredoxin-interacting protein (TXNIP) are part of the thioredoxin antioxidant system, which is involved in DN. We included 897 Slovenian patients with T2DM lasting more than 10 years in our preliminary study. In total, 344 patients with DN were included in our case group, while 553 without DN comprised our control group. The genotypes of