OBJECTIVES: To evaluate the influence of inadequate metabolic control (IC) in comorbidities and the utilization of resources of patients with diabetes mellitus attended at primary care setting (PCS)in daily practise. METHODS: A retrospective-multicenter population-based study was carried out, involving outpatient records (>30 years) managed at seven PCS during year-2006. NCEP-ATP III recommendations were followed, IC: HbA1c>7%. The control-group was formed with patients without ICs. Main outcomes measures were comorbidity (hypertension, hypercholesterolemia, smoking, obesity, cardiovascular events [CVE], COPD, depression, microvascular complications, etc.), as determined by Charlson-index (severity), clinical parameters (BMI, total-cholesterol, LDL-cholesterol, HDL-cholesterol, glucose, triglycerides), resources utilization (specialist referrals, medical visits, drugs, diagnostic tests) and corresponding costs. Descriptive statistics, logistic regression model and analysis of covariance (ANCOVA) with Bonferroni correction were applied, using SPSSWIN v-12.0 and a statistical significance of p<0.05. RESULTS: A total of 5277 patients (age: 67.1±12.0 years, women: 49.7%) were included in the analysis. 30.4% had IC (CI95%: 29.2-31.6%) and 25.0% (CI95%: 23.8-26.2%) suffered a CVE. Patients with IC: Charlson-index 1.2±0.4 vs. 1.1±0.5 and CVE 0.4±0.7 vs. 0.3±0.7, p<0.0001. Logistic regression showed the association between IC and the existence of a stroke (OR=1.3, CI95%: 1.1-1.6), smoking (OR=1.4, CI95%: 1.2-1.6) and retinopathy (OR=1.5, CI95%: 1.2-1.8), p<0.001). Clinical parameters in patients with/without IC, respectively: BMI 30.5±5.5 vs. 29.9±4.9 kg/m2, glucose 176.4±59.0 mg/dl vs. 128.1±30.9 mg/dl, triglycerides 175.0±150.4 vs. 143.2±91.7, total-cholesterol 195.5±44.2 vs. 189.4±38.2, LDL-c 110.0±37.2 vs. 106.8±33.8 mg/dl (p<0.002). Total cost/patient/year adjusted (age-sex, morbidity) was: €1612.18 (CI95%: €1490.48-1733.88) vs. €1937.49 (CI95%: €1829.53-2045.45), pharmaceutical cost represents a 71.5% (€1151.10-1437.91), p=0.001. CONCLUSION: IC in patients with diabetes mellitus is prevalent and it is associated with smoking, stroke and retinopathy. Therapeutic goals have a worse profile in these patients, despite of taking more medicines. GPC should promote specific interventions in this group of patients.