OBJECTIVE To make a preliminary diagnosis of the quality of care that individuals with diabetes mellitus (DM) received in participating centers of the QUALIDIAB network in Latin America and the Caribbean, and to assess the potential usefulness of this information as well as the importance of expanding the QUALIDIAB network. METHODS A total of 13,513 patient records from the QUALIDIAB network were analyzed, from public and private health care entities and from the Social Security systems of Argentina, Brazil, Chile, Colombia, Paraguay, and Uruguay. The study utilized: 1) quality-of-care indicators based on international reference values, 2) patient information on clinical, biochemical, and therapeutic parameters and on the rate of use of diagnostic and therapeutic materials, 3) a computer database program, and 4) a software program for statistical analysis. RESULTS Among the patients studied, about half of them had suffered from diabetes for 5 years or less; this was true both for persons with type 1 diabetes (DM1) and for those with type 2 diabetes (DM2). Of the persons with DM1, 24% of them had a blood glucose level of < 4.4 mmol/L; this was true for 15% of those with DM2. The proportion of persons with a blood glucose level of > 7.7 mmol/L was 41% among those with DM1 and 57% among those with DM2. The frequencies of association between DM2 and other cardiovascular risk factors were: overweight/obesity, 59%; hypertension, 60%; total cholesterol > 5.5 mmol/L, 53%; high-density lipoprotein cholesterol < 1 mmol/L, 32%; triglycerides > 1.7 mmol/L, 45%; and smoking, 13%. Of the people with DM1, 20% of them had a body mass index < 19 kg/m2, probably reflecting deficient metabolic control and inadequate insulin intake. The systematic checking of metabolic control, other cardiovascular risk factors, and chronic DM complications was inadequate in from 3% to 75% of the cases, depending on the specific aspect considered. According to various patient-therapy-education indicators, only some one-quarter to one-half of the studied patients could play an active, effective role in DM control and treatment. Of the persons with DM1, 50% of them were treated with a mixed dose of insulin (NPH + regular insulin), administered in two daily injections in 43% of the cases. Among the patients, 5% of them received one daily insulin injection, and 9% of them received three daily insulin injections. Of the people with DM2, 13% of them treated it only with diet and 14% just with insulin. Among the patients receiving drug treatment, the oral hypoglycemics most used in monotherapy were sulfonylureas (33%), biguanides (9%), and a combination of these two (14%). Fewer than half of the people with diabetes received drug therapy for the associated cardiovascular risk factors. The frequency of patients' macroangiopathic and microangiopathic complications increased with the duration of their disease. Comparing patients who had had diabetes for 5 years or less with those who had had the illness for more than 20 years, the frequency of renal insufficiency and of amputations was around 7 times as great in the latter group; for peripheral neuropathy, it was 2 times as great, and for stroke 1.6 times as great. CONCLUSIONS These results show the need to improve the quality of care for diabetic patients in Latin America and the Caribbean, and that QUALIDIAB could help do this. Expanding the QUALIDIAB network will help to more accurately diagnose the quality of that care in the Americas, and it will facilitate interventions aimed at optimizing the care. This, in turn, will improve the quality of life of persons who suffer from diabetes as well as diminish the socioeconomic costs of the disease.