OBJECTIVES: To assess the causes for referral of type 2 diabetes (T2DM) patients from primary care (PC) to specialized care (SC) in Spain. To assess the degree of compliance with referral quality markers established in national guidelines/recommendations.  METHODS: Observational, cross-sectional, multi-centre national study, in PC and SC. Each physician provided data on usual practice for T2DM patient referral and clinical status of patients with T2DM for 6 referred patients. Inclusion criteria for patients were: written consent, previous T2DM diagnosis and age over 18; exclusion criteria: T1DM, MODY, LADA and secondary diabetes. Recommendations of the Spanish Society for Endocrinology and Nutrition (SEEN) and the National Health System (SNS), were used as reference documents to assess compliance. RESULTS: Data from clinical practice of 143 endocrinologists and 641 general practitioners (GPs), and from referrals of 805 patients to PC and 3624 to SC are presented. PC to SC referrals: 31.8% of GPs reported the existence of a coordination protocol with endocrinologists. The most frequent communication tool with SC was Consultation Report (89.2%). The referral criterion that most GPs reported to apply in usual practice was Metabolic Instability (80.5%). The most frequent cause for referral among the patients studied was Reassessment (48.4%), a criterion not included in national guidelines. 46.8% of GPs applied in usual practice all SNS, 3.9% all SEEN referral criteria. SC to PC referrals:  46.2% of endocrinologists reported the existence of a coordination protocol with PC. The most frequent communication channel with PC was Medical History (47.2%).  The referral criterion reported by a higher number of endocrinologists (96.5%) was Goal Achievement, most frequent cause for referral also among the patients studied. CONCLUSIONS: These findings emphasise the need of improving coordination processes to optimize and homogenize referrals. The number of reported coordination protocols is low, and the compliance with national guidelines poor.