Background and aimsDiabetes mellitus is a prevalent chronic disease in patients who die of COVID-19. The aim of this study was to investigate the clinical and metabolic characteristics of diabetic patients with COVID-19 during the pre-vaccination phase. Methods and resultsA retrospective cohort study was conducted from February 2020 to February 2021 to examine the clinical and metabolic profiles of unvaccinated diabetic patients affected by COVID-19. Data were collected from claim databases, hospital discharge records, and clinical records within a healthcare district located in northeastern Italy with a population of 936,000. Potential prognostic indicators including sex, age, Body Mass Index (BMI), duration and type of diabetes, metabolic control, and the use of antidiabetic, antihypertensive, lipid-lowering, and antiplatelet therapies were investigated. For hospitalized patients, additional variables were recorded, such as length of hospital stay, blood pressure at admission, comorbidities, D-dimer levels, blood glucose (BG), in-hospital insulin and corticosteroid therapies, requirement for mechanical ventilation (i.e., orotracheal or tracheostomy), admission to the Intensive Care Unit (ICU), and mortality. Diabetic patients hospitalized for COVID-19 with a poorer prognosis were characterized by advanced age, longer diabetes duration, hypertension, higher usage of sulfonylureas, and lower usage of dietotherapy alone, metformin, Glucagon-Like Peptide-1 Receptor agonists (GLP1-Ra), and Renin-Angiotensin-Aldosterone System inhibitors (RAAS-i). ConclusionConsidering the potential for COVID-19 to become endemic, special care should be taken in managing older diabetic patients’ treatments.