OBJECTIVE To determine the impact of primary care on hospitalization of type 2 diabetics with equal conditions of health insurance. DESIGN A case-control study. Case = diabetic hospitalized by a disease related condition. Control = diabetic without hospitalization during the last 12 months. SETTING Urban primary care centers. PARTICIPANTS Cases were consecutively selected from four out of five urban hospitals (n=123). Controls were chosen at random from primary care units matched by primary care source (n=135). Women with gestational diabetes were excluded as well as individuals with missing medical charts (approximately 15%). MEASUREMENTS A primary care index was constructed with process and outcome indicators recommended by the American Medical Association, the Joint Commission on Accreditation of Healthcare Organizations, the National Committee for Quality Assurance, the American Diabetes Association and the Official Mexican Standards. Compliance to less than 60% of recommendations was considered unsatisfactory primary care. RESULTS The following were hospitalization risk factors: less than 2 visits to family physician during the last year (OR adjusted, 16,2; 95% CI, 1,5-174,2), glucose level (OR adjusted, 1,006; 95% CI, 1,002-1,010) and cognitive level (OR adjusted, 0,98; 95% CI, 0,96-0,99), in addition to exercising and year of diagnosis. Sixty-five percent of cases observed unsatisfactory primary care compared with 49,1% of controls (P=0,03). Unsatisfactory primary care increased 2,5 times the risk of hospitalization (95% CI, 1,2-5,0) (pseudo R2=0,279; P<0,001). CONCLUSIONS Primary care is a potential factor for reducing hospitalization of type 2 diabetics. Effective primary care programs would contribute to a better disease control and less unnecessary hospitalizations.