To determine the reasons for hospitalisation in those with diabetes who contract COVID-19.We analysed all COVID-19 cases reported to the Victorian Department of Health and linked hospitalisation data. We determined reasons for acute (0-30 days) and post-acute (31-365 days) hospitalisation among those with type 1 or type 2 diabetes and COVID-19, compared to those with COVID-19 and no diabetes, and to admissions prior to the COVID-19 pandemic.13,302 Australians with type 1 or type 2 diabetes were hospitalised in the state of Victoria in the 12 months after COVID-19 diagnosis. Respiratory diseases accounted for 40% of acute admissions among those with diabetes. Viral pneumonia was the leading reason for acute hospitalisation among those with diabetes and constituted a larger proportion of admissions in those with diabetes compared to those without (adjusted PR 1.87, 95% CI 1.76 - 1.99). The distribution of post-acute hospitalisations among those with diabetes aligned with that of people with diabetes prior to the COVID-19 pandemic.Respiratory diseases are the leading reason for acute hospitalisation in those with type 1 or type 2 diabetes and COVID-19. The reasons for post-acute hospitalisation resemble those in people with diabetes and no COVID-19. We reinforce the importance of community management of people with diabetes in the ongoing pandemic.