Effect of glucose lowering on coronary vascular function, carotid intima-media thickness and coronary artery calcification in type 2 diabetes mellitus

Objectives To determine the effect of plasma glucose lowering with glyburide and metformin on coronary circulatory function, carotid intima-media thickness (IMT) and coronary artery calcification (CAC) in diabetes mellitus after a 1 year follow-up.

Methods In twenty-two type 2 diabetes coronary circulatory function was determined with PET- measured myocardial blood flow (MBF) responses to cold pressor testing (CPT) and during adenosine (ADO). Carotid IMT was assessed with vascular ultrasound and CAC with electron beam tomography (EBT).

Results Plasma glucose decreased from 205±72 to 160±44 mg/dl that resulted in a significant increase in endothelium-related MBF response to CPT and to ADO (DMBF) (0.09±0.09 vs. 0.19±0.17 and 1.19±0.51 ml/g/min, p<0.05), while carotid IMT and CAC had mildly increased (0.83±0.19 vs.0.86±0.18mm2 and 35.3±68 vs. 59.9±102 HU). The decrease in plasma glucose levels correlated with an improvement in DMBF to CPT and to ADO (r=0.46, p<0.038 and r=0.36, p<0.056) and, also with a lower progression of carotid IMT and CAC (r=0.46, p<0.055 and r=0.48, p<0.036).

Conclusions In type 2 diabetes mellitus, glucose lowering improves coronary circulatory dysfunction, while it may also slow the progression of early structural alterations of coronary atherosclerotic disease.