Vein graft patency has been reported in some studies to be diminished in patients with diabetes mellitus and the metabolic syndrome.279 This may relate to the association between type 2 diabetes mellitus and impaired endothelial function and intimal degeneration of saphenous vein grafts, changes that inversely correlate with the metabolic control of the diabetes mellitus.280 Interestingly, diabetes mellitus has much less effect on the properties of the internal mammary artery. In a long-term patency evaluation of 501 CABG patients, Lytle et al281 noted that insulin-dependent diabetes mel- litus was associated with late vein graft failure (P<0.004). Nevertheless, the adverse effects of diabetes mellitus on graft patency have not been seen in all studies. For example, in a 10-year follow-up of the VA Cooperative Study involving 1074 CABG patients, Goldman et al282 did not find diabetes mellitus to be an independent predictor of vein graft failure. Most recently, in a long-term observational study evaluating risk factors for adverse outcomes after CABG, Sabik et al164 reported that diabetes mellitus was a strong risk factor for cor- onary reintervention (either percutaneous coronary interven- tion or redo CABG) in the years after CABG. Patients treated with insulin or oral medications had a similarly elevated risk of undergoing reintervention (P<0.0001), whereas patients with diet-controlled diabetes mellitus also had an increased risk of reintervention, but lower than the risk in those treated pharma- cologically (P=0.005). Whether the degree of glucose control independently predicts vein graft patency remains unclear.283 This uncertainty likely relates to the difficulty in separating the effects of glucose control from the progression of cardio- vascular disease in general but may also be complicated by the challenges and inaccuracy of graft patency assessment, small study sample sizes, and separation of the effects of associated conditions such as hyperlipidemia and hypertension. 