OBJECTIVE: Stable microvascular angina (SMVA) describes patients with angina, findings compatible with myocardial ischemia and normal coronary angiograms. The aim of this study was to evaluate the impact of diabetes on the coronary microcirculation troughs angiography indexes (TIMI Frame Count, Myocardial Blush Grade, Total Myocardial Blush Score) and a new index:TotalTIMI Frame Count (TTFC). PATIENTS AND METHODS: The study population included 310 patients with SMVA that we split into two populations: diabetic-non hypertensive (164 patients) and non-diabetichypertensive (146 patients). We calculated, on angiographic images of each patient, TIMI Frame Count (TFC), Myocardial Blush Grade (MBG) and Total Myocardial Blush Score (TMBS) using the protocol described by Gibson and Yusuf. On the basis of Yusuf's experience we imagined a new index:TTFC like sum of the three coronary TFC. RESULTS:We found a worse coronary microcirculation in diabetic-non hypertensive patients with lower values of TFC, MBG and TMBS (p = 0.02), compared with non-diabetic hypertensive. New index TTFC is usually higher in diabetic-non hypertensive than non-diabetic hypertensive patients. Patients with positive scintigraphy had a worse TMBS than patients with a negative one, with a high statistical significance (p = 0.003). CONCLUSIONS: Analysis of diabetic non hypertensive and non-diabetic and hypertensive patients with cardiac syndrome X has led to asses that the diabetic population has a greater involvement of microcirculation. Also the new index, TTFC, proved to be a good marker, in agreement with results of other indexes.