OBJECTIVES To investigate the burden of type 1 diabetes mellitus (T1DM) in France associated with non-adherence to clinical guidelines using the IMS CORE Diabetes Model (CDM) and clinical data from the IMS Lifelink Diabetes Cohort. METHODS The CDM is a health economic model based on 17 inter-dependent sub-models that simulate micro- and macrovascular complications associated with diabetes. Physiological parameter inputs such as HbA1c, blood lipids, body mass index (BMI), and systolic blood pressure (SBP) were taken from real-life data and compared with guidelines from the “Haute Autorité de Santé”. T1DM patients (age ≥ 18) who visited a general physician between May 2011 and May 2014 and have received at least one insulin prescription were included in the analysis. Costs and outcomes were discounted at 4% per annum. Costs of complications were taken from published sources. RESULTS A cohort of 605 T1DM patients (43% male) was analyzed. Mean age at first visit was 58 years, HbA1c was 7.8%, SBP was 132 mmHg, and BMI was 28 kg/mCONCLUSIONS The “Haute Autorité de Santé” recommends that T1DM patients maintain their HbA1c lower than 7.5%, SBP lower than 130 mmHg, BMI lower than 25 kg/m and quit smoking. Our results showed that these recommendations were not strictly followed among T1DM patients in France. Better adherence to the T1DM guidelines would lead to cost savings in the French healthcare system and improved patient outcomes.