Relationship between HbA1c and coronary flow rate in patients with type 2 diabetes mellitus and angiographically normal coronary arteries.

OBJECTIVES: We examined the relationship between glycosylated hemoglobin (HbA1c) level and coronary flow rate in patients with type 2 diabetes mellitus (DM) and angiographically normal coronary arteries. STUDY DESIGN: The study included 54 consecutive patients (36 males, 18 females; age range 37 to 72 years) with type 2 DM, whose coronary arteries were found normal on coronary angiography. All patients underwent echocardiography and plasma HbA1c levels were measured before coronary angiography. To determine slow coronary flow (SCF), coronary flow rates of the left anterior descending (LAD), circumflex (Cx), and right coronary (RCA) arteries were assessed using the TIMI frame count (TFC) method. RESULTS: None of the patients had echocardiographic abnormalities. The mean HbA1c level was 7.4±2.0%, and the mean TFCs were 34.3±6.5, 22.4±3.5, and 20.4±2.2 for the LAD, Cx, and RCA, respectively. HbA1c levels were <7% in 26 patients, and ≥7% in 28 patients. Thirty-eight patients (70.4%) were found to have SCF in at least one coronary artery. TIMI frame counts of all three coronary arteries were significantly greater in patients in whom HbA1c was ≥7% (p<0.001). TIMI frame counts showed significant correlations with the HbA1c level (LAD: r=0.782; Cx: r=0.707; RCA: r=0.515; p<0.001 for all). The mean HbA1c level was significantly higher in patients with SCF compared to patients without SCF (7.8±1.9% vs. 5.6±0.9%; p<0.001). The incidence of SCF was significantly greater in patients with HbA1c ≥7.0% than those with HbA1c <7.0% (96.4% vs. 61.5%; p=0.004). Increased HbA1c (≥7%) significantly increased the risk for SCF in at least one coronary artery (OR=16.875; 95% CI 1.972-144.38). CONCLUSION: Our findings suggest that there is a strong correlation between the HbA1c level and coronary flow rate.