Objective: Several decision-theoretic models exist to assess the long-term outcomes and economics of diabetic interventions. Since the models are proprietary, users are limited in their ability to critically review program code and modify inputs for their specific setting. The main objective was to develop a diabetes model with open-source code that is unlocked, transparent, and modifiable by users, which are important considerations for pharmaceutical decision makers, particularly in Canada. Methods: The analytical framework is similar to the United Kingdom Prospective Diabetes Study (UKPDS)-based model (Clarke et al., Diabetologia 2004), and is created in Microsoft Excel, using visual basic. It is adaptable to both individual- and cohort-level data. Relationships between outcomes (e.g., myocardial infarction) and exogenous variables (e.g., HbA1c) were based on the equations as reported by Clark et al. The model was further modified to include (1) costs and disutilities associated with hypoglycemia and (2) options for emerging treatment intensification regimens as the patient’s diabetes progresses.  The model uses Canadian resource use data as defaults. The model was validated against the findings of the Ontario Diabetes Economic Model (ODEM, http://www.path-hta.ca/diabetes.pdf, 2006). Results:  The quality-adjusted life-year gain of 8.23 for the control arm in published results of ODEM fell within the 95% confidence interval of (8.20, 8.29) generated by the model. The corresponding results for life-years gained are also concordant. Unlike previous diabetes models, our model fulfills Canadian drug submission requirements, specifically the strict guidelines of the Common Drug Review (CDR) agency. Conclusion: An open-source, interactive diabetes model will greatly facilitate users’ – specifically clinicians and other decision makers  – ability to modify inputs specific to their setting and rigorously assess the validity of findings.