Due to its prevalence and socio-economic burden on health systems, diabetes mellitus (DM) is considered a major health emergency. This retrospective, observational study aimed to describe a population of DM-naïve patients of the Local Health Authority (LHA) ASL TO4 Regione Piemonte and the prescriptive behavior of LHA general practitioners. Drug dispensing data collected between January 2018 and December 2021 was analyzed. Adult patients were included if they received their first prescription for an antidiabetic drug (AD) in 2019 and had ≥2 prescriptions/year of ADs during the follow-up. Patients who started antidiabetic therapy with metformin were selected to investigate comorbidities, medication adherence, and first treatment intensification. Comorbidities were identified through a modified version of the Rx-Risk Index; adherence was measured as the continuous measure of medication availability (CMA). Among 1927 DM-naïve patients, 1361 started therapy with metformin. Most of them received drugs related to cardiovascular diseases, hypertension, and infectious diseases during the study period. Median CMA was 58.8%, with the majority of patients being partially adherent to ADs (40 ≤ CMA < 80). Initial antidiabetic therapy was mostly modified (switch, add-on) with SGLT-2 inhibitors and sulfonylureas. These findings help to identify areas of intervention to improve the use of ADs in the LHA.