Many middle-income countries are experiencing an increase in diabetes mellitus but patterns of morbidity and resource use from diabetes in developing countries have not been well described. We evaluated hospital admission with diabetes among different ethnic groups in Trinidad. We compiled a register of all patients with diabetes admitted to adult medical, general surgical, and ophthalmology wards at Port of Spain Hospital, Trinidad. During 26 weeks, 1447 patients with diabetes had 1722 admissions. Annual admission rates, standardized to the World Population, for the catchment population aged 30-64 years were 1031 (95% CI 928 to 1134) per 100,000 in men and 1354 (1240 to 1468) per 100,000 in women. Compared with the total population, admission rates were 33% higher in the Indian origin population and 47% lower in those of mixed ethnicity. The age-standardized rate of amputation with diabetes in the general population aged 30-64 years was 54 (37 to 71) per 100,000. The hospital admission fatality rate was 8.9% (95%CI 7.6% to 10.2%). Mortality was associated with increasing age, admission with hyperglycaemia, elevated serum creatinine, cardiac failure or stroke and with lower-limb amputation during admission. Diabetes accounted for 13.6% of hospital admissions and 23% of hospital bed occupancy. Admissions associated with disorders of blood glucose control or foot problems accounted for 52% of diabetic hospital bed occupancy. The annual cost of admissions with diabetes was conservatively estimated at TT+ 10.66 million (UK 1.24 million pounds). In this community diabetes admission rates were high and varied according to the prevalence of diabetes. Admissions, fatalities and resource use were associated with acute and chronic complications of diabetes. Investing in better quality preventive clinical care for diabetes might provide an economically advantageous policy for countries like Trinidad and Tobago.