Background: the relationship between coronary Slow flow (CSF) and insulin resistance still a subject of debate with conflicting data. Aim: To assess the relationship between insulin resistance ( IR) as measured by insulin resistance index (HOMA-IR) and coronary slow flow as measured by the TIMI frame count in patients which ( impaired glucose tolerance (IGT )and insulin resistance. Methods: 87 Consecutive patients diagnosed as coronary slow flow as evidenced by invasive coronary angiography after excluding coronary plaque or obstructive coronary artery disease or overt diabetes mellitus were assigned to either IGT or to NGT group. The primary endpoint was assessing the relationship between insulin resistance as measured by insulin resistance index (HOMA-IR) versus coronary slow flow as measured by the TIMI frame count. Results: Out of 87 patients enrolled; 64 (73.6%) patients were assigned to the IGT group while 23 (26.4%) patients were assigned to the NGT group. There were significantly higher: BMI (30.15 ±2.29 Vs 23.90±2.5, P<0.001); waist circumference (105.05±9.0.06 vs 92.92 ±16.5, P <0.001); frequency of hypertension (60.9% vs 34.8, P=0.03). Also there were significantly higher: 2hPP glucose (161±30 vs 110 ±20, P<0.05); fasting serum insulin level (9.56±2.5 vs 7.03±2.1, P<0.001); HDL (40 ±6.5 vs 49± 5.6, P<0.001); HOMA-IR index (2.84±0.03 vs 1.6 ±0.05, P<0.05); mean TIMI frame count (33±5 vs 26±4, P <0.001) among the IGT group. While HDL was were significantly lower in the IGT group ( 40±6.5 vs 49 ±5.6, P<0.001). There was a highly significant positive correlation between TIMI frame count and HOMA-IR.(r=0.43, P<0.001); predictors that add significance to the model were: age >50 years; hypertension; high waist circumference; HDL< 35; and HOMA-IR. for HOMA-IR, (OR 95% CI = 1.9 (1.05-3.49), P=0.02 demonstrating that, HOMA-IR is a powerful independent predictor of high TIMI frame count (table 4). Conclusion and recommendation: Insulin resistance is an independent risk factor for slow coronary flow in patients with IGT. Those with evident coronary slow flow, IGT should be managed aggressively even before any evidence of frank diabetes .Also, IR workup should be recommended among the other standard workup for those patients, if documented, Targeting I.R in such patients should be a priority (whenever possible) while selecting medications for comorbid cardiac disease , as well as using interventions targeted against IR should be considered among the other standard management for slow flow .