Heart failure is a prevalent comorbidity in patients with diabetes mellitus (DM). However, it is unclear whether the risk factors for heart failure in DM patients treated with dipeptidyl peptidase-4 (DPP-4) inhibitors are the same as those for the general population. In this study, we evaluated the factors of new-onset heart failure in working-age patients with diabetes who started DPP-4 inhibitor therapy. This study included 7938 working-age patients. The primary endpoint of the study was the proportion of patients developing heart failure within 12 months of starting DPP-4 inhibitor therapy, which was found to be 1.89% (n 150). In these patients, risk factors of new-onset heart failure were aging, history of atrial fibrillation, and hypertension but not sex, smoking, high body mass index, weight gain of over 10 kg from 20 years of age, levels of low-density lipoprotein or glycated hemoglobin A1c (HbA1c), history of angina pectoris, myocardial infarction, and chronic kidney disease. We confirmed that cardiovascular comorbidities are risk factors for new-onset heart failure in patients with DM, while general risk factors are not. In conclusion, physicians and pharmacists need to carefully monitor working-age patients with cardiovascular history who start DPP-4 inhibitor therapy even if they do not exhibit general risk factors for heart failure.