To analyze national trends in the rates of hospitalizations (all-cause and by principal discharge diagnosis) in total diabetic population of Spain. We carried out a nation-wide population-based study of all diabetic patients hospitalized between 1997 and 2010. All-cause hospitalizations, hospitalizations by principal discharge diagnosis, mean age, Charlson Comorbidity Index, readmission rates and length of hospital stay were examined. Annual rates adjusted for age and sex were analyzed and trends were calculated. Over 14-years-period, all-cause hospitalizations of diabetic patients increased significantly, with an average annual percentage change of 2.5 (95%CI: 1.5–3.5; Ptrend < 0.01). The greatest increase was observed in heart failure (5.4; 95%CI: 4.8–6.0; Ptrend < 0.001), followed by neoplasms (4.9; 95%CI: 3.6–5.8; Ptrend < 0.001), pneumonia (2.7; 95%CI: 2.0–4.0; Ptrend < 0.001), stroke (2.4; 95%CI: 1.6–3.4; Ptrend < 0.001), chronic obstructive pulmonary disease (2.0; 95%CI: 1.4–3.4; Ptrend < 0.001) and coronary artery disease (1.6; 95%CI: 1.1–2.3; Ptrend < 0.01). The adjusted number of all-cause hospitalizations of patients with diabetes per 100,000 inhabitants increased 2.6-fold. The increase in hospitalizations was significantly higher among patients ≥75 years old. Males experienced a greater increase in all-cause, neoplasm, heart failure, chronic obstructive pulmonary disease, and pneumonia hospitalizations (p < 0.01 for all). Hospitalized diabetic patients were progressively older and had more comorbidities, higher readmission rates and shorter hospital stays (p < 0.05 for all). Hospitalizations of diabetic patients more than doubled in Spain during the study period. Heart failure and neoplasms experienced the greatest annual increases and remained the principal causes of hospitalization, probably associated with advanced age and comorbidities of hospitalized diabetics. Coronary and cerebrovascular diseases experienced a lower annual increase, suggesting an improvement in cardiovascular care in diabetes in Spain. •Patients with diabetes mellitus are admitted to hospital more often.•Hospitalizations of patients with diabetes have gradually increased over time.•Heart failure and neoplasms are the main causes of hospitalizations for diabetics.•Hospitalized diabetic patients are progressively older and have more comorbidities.•Hospitalization trends for coronary and cerebrovascular disease are less pronounced.