The clinical symptoms of COVID-19 infection differ from one patient to another, requiring different management. This study intended to characterize the clinical manifestation of COVID-19 in patients with asthma, hypertension, and diabetes mellitus (DM). We analyzed data from 540 medical records of patients with comorbidities like asthma, hypertension, and DM diagnosed with COVID-19, looking at vital signs upon admission, chest X-ray, and laboratory results. Most patients were male (57.0%). The most prevalent comorbidity was hypertension (46.3%) and DM (46.3%), followed by asthma (7.4%). 273 patients had improved condition (50.6%). Patients with hypertension had the most extended length of stay compared to other comorbidities groups (13.0±8.5 days). There were significant differences in the oxygen saturation and respiration rate between the three groups (p=0.002, p<0.0001, respectively). The mean lymphocyte (p=0.028) and hematocrit count (p=0.001) were significantly different between the three comorbid groups, with the hypertension group having the highest mean lymphocyte (15.1±8.9) and hematocrit (38.7±6.9) count. COVID-19 had a significant impact on patients with asthma, hypertension, and diabetes comorbidities concerning the final condition, length of stay, oxygen saturation, and respiratory rate, and also on the hematology level, mainly lymphocyte and hematocrit. Treatment, age, and infection might be determinant factors for different outcomes in each type of comorbidity.