OBJECTIVE To estimate the self-reported weighted prevalence of diabetes mellitus among different population subgroups and determine associated factors in Puerto Rico. METHODS Data gathered from the Behavioral Risk Factor Surveillance Survey (BRFSS) during 1999 was analyzed. RESULTS The weighted prevalence in Puerto Rico in 1999 was 9.6% (95% CI: 8.5%-10.7%), highest than reported nationally. It was higher among individuals with increasing age, female sex, decreasing annual income, decreasing educational attainment, being non-employed, having a health care coverage, high blood pressure, high blood cholesterol, and increasing body mass index. Health behaviors and co-morbid conditions significantly associated with diabetes among individuals aged less than 65 years were high blood pressure, high blood cholesterol, obesity and low educational attainment. However, the only significant characteristic associated with diabetes in individuals aged 65 years or more was female sex. Analysis of the data gathered in the diabetes module revealed that nearly 35% were using insulin, 57.4% were using insulin once a day, 14.4% self-monitored their blood glucose one to three times per day, 18.3% reported they have heard of the glycosylated hemoglobin test, and of these, 71.8% had their test performed between one and six times within the past year. Nearly 42% reported their feet were checked and 54.1% had a dilated eye examination last year. CONCLUSION The high prevalence of diabetes in Puerto Rico underscores the need for developing integrated management strategies for improving quality of diabetes care.