The consumption of dairy proteins, particularly those from whey, has been shown in interventional studies to have beneficial effects on glucose metabolism. It has been proposed that the antidiabetic properties of whey protein may be attributable to its content of bioactive peptides which, upon being released during digestion, can modulate hormones, enzymes and/or organ systems involved in glycemia regulation. In particular, recent studies have suggested that milk protein-derived peptides can inhibit the activity of the dipeptidyl-peptidase IV (DPP-IV) enzyme, a target in the management of type 2 diabetes. The aim of this study was to evaluate the potential of bovine immunoglobulins (Ig) and glycomacropeptide (GMP) to serve as precursors of peptides with DPP-IV inhibitory activity. Ig and GMP were first submitted to in vitro gastrointestinal (GI) digestion and the resulting digests assessed for their effect on DPP-IV activity. While undigested proteins showed no effect on DPP-IV, both digests were able to inhibit the enzyme, the Ig digest displaying the greatest potency (IC₅₀ = 0.6 and 1.0 mg/mL, for the Ig and GMP digests, respectively). Ultrafiltration of the digested proteins to further characterize them revealed peptide fractions with varying degree of effectiveness against DPP-IV, none being, however, more potent than the whole digests they originated from. Findings from this research show that DPP-IV-inhibiting peptides can be generated during GI digestion of Ig and GMP and suggest that the consumption of these milk constituents could have a beneficial effect on blood glucose regulation.