Background: Diabetes mellitus may be associated with increased severity and enhanced mortality in COVID-19 infections. The present study was undertaken to evaluate the clinical presentation, laboratory parameters, radiological imaging, management, and outcome of COVID-19 infection in patients of diabetes mellitus and its association with glycemic control. Methods: The present study was designed to evaluate the difference between uncontrolled and controlled diabetes for COVID-19 manifestations by enrolling 80 admitted COVID-19 patients. Patients were categorized into two groups, where group 1 had patients with uncontrolled diabetes as indicated by HbA1c > 8 g% and group 2 had patients with controlled diabetes as indicated by HbA1c < 8 g%. Information concerning medical history, clinical manifestations, laboratory findings, radiological imaging, management, and outcome was extracted from medical records for evaluation, interpretation, and association among both the groups. Results: COVID-19 patients with uncontrolled diabetes exhibited a severe symptomatic presentation, excessive uncontrolled inflammatory responses, and hypercoagulable state. Total leukocyte count, neutrophil-lymphocyte ratio, serum levels of IL-6, FDP, and D-dimer were significantly raised (p < 0.05) in case of uncontrolled diabetes as compared with controlled diabetes. Radiological findings detected by chest radiograph and computed tomography chest suggested severe lung involvement in uncontrolled diabetes. COVID-19 patients with uncontrolled diabetes required intensive treatment as compared with controlled diabetes group in terms of insulin therapy (p = 0.0226) and non-invasive ventilation (p = 0.0292). Patients with uncontrolled diabetes had higher mortality (p = 0.0375) and required prolonged hospitalization (p = 0.0479) as compared with controlled diabetes group. Conclusion: From the current study, it can be concluded that uncontrolled diabetic condition might be a risk factor for severity and morbidity of COVID-19 patients. Uncontrolled diabetes mellitus might be responsible for an overall higher susceptibility for COVID-19 infection and severity in terms of symptomatic presentation, inflammatory storm, rapid pulmonary invasion, requirement of more intensive treatment, and a poor outcome.