The COVID-19 infection is a double challenge for people infected with comorbidities such as cardiovascular, cerebrovascular and diabetes. Comorbidities have been reported to be risk factors for the complications of COVID-19 infection. In most cases, people with diabetes have much higher rates of serious complications, low rate of recovery and higher mortality rate compare to people without diabetes. According to WHO data from 13 countries evaluated, revealed that 10.2% case of death of patients with and diabetes compared of 2.5% death of patients with COVID-19 only. In this paper, we formulate a mathematical model of COVID-19 and diabetes comorbidity under vaccination. This model will contribute to knowledge in mathematics, which will be used by researchers for future references and analysis.