<p>Trace elements play a vital role in maintaining metabolic health by regulating glucose metabolism, enhancing insulin sensitivity, and supporting antioxidant defense. Moreover, they act as protective shields against toxic metal-induced oxidative stress, where even slight imbalances can shift the body from metabolic harmony to diabetes progression. This prospective case–control study was conducted at the Department of Biochemistry in collaboration with the Department of General Medicine at the North Indian Tertiary Care Centre. This study included 473 newly diagnosed type 2 diabetic patients (T2DM) and 303 controls. Serum toxic and trace elements were analyzed using inductively coupled plasma mass spectrometry. HbA1c was measured using ion-exchange high-performance liquid chromatography, while fasting serum insulin and glucose levels were measured using Cobas 6000, Roche Diagnostics to calculate insulin resistance and beta-cell dysfunction. Toxic elements (Nickel and Arsenic) and trace elements (Selenium, Molybdenum, Chromium, and Copper) were significantly elevated, while Manganese (Mn) was significantly reduced in the T2DM group compared to the controls (<i>p </i>&lt; 0.0001, respectively). Nickel (Ni) and arsenic (As) were independently associated with HbA1c and insulin resistance in multivariate analysis. Among the trace elements, only Mn remained independently but was negatively associated with HbA1c. With β-cell function as the outcome, As remained negatively associated, and Mn remained positively associated. Gaussian process classifier and Bayesian kernel machine regression analysis further verified that Mn antagonizes diabetes risk associated with Ni and As exposures. Targeting trace element homeostasis, particularly enhancing Mn status, may open new avenues for the prevention and therapeutic intervention of T2DM.</p>