To determine the status of diabetes care by general practitioners and diabetes specialists in Japan, we conducted a nation-wide cross-sectional survey. We asked 8112 clinics and hospitals randomly, from throughout Japan, to participate in this study and 721 facilities agreed. A total of 15,652 patients aged from 15 to 97 with type 1 and type 2 diabetes were enrolled. Of these, 14,560 (93.0%) and 1092 (7.0%) patients were cared for by general practitioners and diabetes specialists, respectively. HbA1c levels were measured by a latex agglutination method, and age, height, body weight, type of diabetes and treatment modality were obtained from each patient. Mean HbA1c level for all patients treated by general practitioners was significantly lower than for those treated by the diabetes specialists (6.8+/-1.2% vs. 7.0+/-1.2%, p=0.0002). Mean HbA1c level for patients without insulin therapy was lower than for those treated with insulin, irrespective of caring physician. The proportion of patients treated with insulin therapy by diabetes specialists was higher (17.7%) than that by general practitioners (6.5%). This study showed that average HbA1c levels in Japanese patients treated by either general practitioners or specialists was acceptable, regardless of study limitations or bias.