Background: Type 2 Diabetes Mellitus (T2DM) is a prevalent metabolic disorder in Northern India, with a significant portion of the population relying on oral antidiabetic drugs. However, the occurrence of adverse drug reactions (ADRs) poses a critical challenge to effective diabetes management. This study aimed to evaluate the prevalence, severity, and causality of ADRs among T2DM patients in a tertiary care setting in Northern India. Methods: A prospective observational study was conducted over 12 months involving 227 T2DM patients receiving oral antidiabetic drugs. Data were collected through patient interviews, medical records, and structured questionnaires. The ADRs were assessed for their frequency, severity using the Modified Hartwig and Siegel Scale, and causality using the WHO-UMC Causality Assessment Tool. Chi-square and ANOVA tests were employed to analyse the association of ADRs with demographic factors, drug classes, and polypharmacy. Results: The study found a significant prevalence of ADRs, particularly associated with Biguanides, Sulfonylureas, SGLT2 Inhibitors, and GLP-1 Receptor Agonists. Common ADRs included gastrointestinal disturbances, hypoglycaemia, and weight gain. No significant differences in ADR occurrence were found based on age or gender. However, polypharmacy was significantly associated with a higher risk of ADRs, emphasizing the need for careful medication management. Conclusion: The findings highlight the critical need for robust pharmacovigilance and personalized treatment strategies in managing T2DM in Northern India. Tailored therapeutic approaches and vigilant monitoring can enhance patient safety and optimize treatment outcomes.