Coronary blood flow is slower in prediabetic and diabetic patients with normal coronary arteries compared with nondiabetic patients.

OBJECTIVE: To compare coronary blood flow in diabetic, prediabetic and nondiabetic patients with angiographically normal coronary arteries.
METHODS: In the present retrospective study, 759 patients with normal coronary arteries who underwent coronary angiography between January 2010 and July 2011 were enrolled. The angiograms of eligible patients were reviewed again for thrombolysis in myocardial infarction (TIMI) frame counts. Patients were subsequently grouped according to their diabetes mellitus (DM) status: group 1 nondiabetic; group 2 prediabetic; and group 3 DM.
RESULTS: TIMI FRAME COUNTS FOR EACH OF THREE CORONARY ARTERIES WERE FOUND TO BE SIGNIFICANTLY DIFFERENT AMONG GROUPS USING ANOVA TESTING (CORRECTED TIMI FRAME COUNTS FOR LEFT ANTERIOR DESCENDING ARTERY AND TIMI FRAME COUNTS FOR LEFT CIRCUMFLEX AND RIGHT CORONARY ARTERIES, RESPECTIVELY, IN THREE GROUPS: group 1 20.2±6.8, 18.8±5.4 and 19.9±8.7; group 2 22.2±8.0, 20.8±7.9 and 22.2±8.8; group 3 22.3±9.2, 21.6±10.2 and 22.3±10.6; P<0.01 for each coronary artery). When the groups were compared with one another using post hoc tests, group 2 and group 3 had similar TIMI frame counts for all three coronary arteries, but both of these groups had significantly higher TIMI frame counts than group 1 (P for each comparison was <0.017).
CONCLUSIONS: The present study has, for the first time, shown that coronary flow measured by TIMI frame count is slower in prediabetic patients than in nondiabetic patients, and is similar to coronary flow in diabetic patients. This result provides supportive evidence that endothelial dysfunction develops in the prediabetic phase before overt DM manifests.