OBJECTIVE To determine the barriers to optimal care at the community level for patients with non-insulin-dependent diabetes mellitus (NIDDM). METHODS Comprehensive evaluation of the clinical, psychosocial, and educational status of community-based patients with NIDDM, with subsequent review by local diabetes advisory councils of this status and the care those patients have received. The frequency with which patients visited their physician for diabetes management, received patient education, received diet counseling, and were examined by an ophthalmologist-four services universally recognized to be components of optimal diabetes care-was determined for all patients. METHODS Eight Michigan communities, four large and four small. METHODS From 1988 to 1994, 1056 patients with NIDDM defined by stimulated C-peptide criteria) were studied. RESULTS The frequency with which all patients with NIDDM visited their community primary care physician in 1994 was 3.7 times per year (4.6 times for patients taking insulin and 3.2 times for those not taking insulin). Thirty-three percent of all patients with NIDDM (48% of those taking insulin and 24% of those not taking insulin) had received all three other essential services, whereas 15% (6% taking insulin and 20% not taking insulin) had never received any of these services. Factors contributing to this level of care and barriers preventing more intensive management of community-based patients with NIDDM were identified by the diabetes advisory councils as they analyzed data from their own communities. The councils determined that the main barriers to optimal care of community-based patients with NIDDM are that 1) NIDDM is not considered or managed as a serious problem by most physicians and their patients; 2) the genetic basis for and refractory nature of obesity are not generally appreciated; and 3) as a complex, multisystemic chronic illness, diabetes fits poorly in a health care delivery system designed to deal with acute and episodic illnesses. CONCLUSIONS Most community-based patients with NIDDM are not aggressively managed because of attitudinal, educational, and systemic factors that act as barriers to optimal health care delivery.