This case report presents a patient with T2DM who developed diabetic ketoalkalosis following abrupt discontinuation of basal insulin during the initiation of tirzepatide (Mounjaro), emphasizing the need for gradual insulin tapering and close monitoring while transitioning from insulin to GIP/GLP-1 RA in high-risk individuals. The gene discussed is GLP1R; the disease is type 2 diabetes mellitus.