Should postprandial hyperglycaemia in prediabetic and type 2 diabetic patients be treated?

Numerous prospective studies support the concept of postprandial glycaemia (PPG) as a risk factor for cardiovascular diseases (CVDs) in individuals with impaired glucose tolerance (IGT). A meta-analysis has demonstrated an exponential relationship between 2-hour postchallenge glucose levels and the incidence of CVD. This relationship is stronger than those observed with fasting glycaemia or glycosylated haernoglobin (HbA(1c)), and persists after adjustment for other vascular risk factors. Although there are fewer data available for the diabetic population, those that are available also support PPG as a risk factor for CVD. Treating PPG with acarbose is associated with a reduction in cardiovascular events in both patients with IGT and diabetes mellitus. Acarbose also reduces the progression of intima-media thickness (IMT), which is a surrogate endpoint for atherosclerosis. It has been suggested that the beneficial effect could be related to an improvement in postprandial hyperglycaemia and associated atherogenic factors - oxidative stress, endothelial dysfunction and procoagulation factors - and to an improvement in other cardiovascular risk factors such as systolic blood pressure (by decreasing water and salt absorption), postprandial hypertriglyceridaemia and insulin resistance. Treating PPG with glinides improves IMT as well as interleukin-6 and C-reactive protein levels, while treating PPG with rapid-acting insulin analogues is also associated with improvements in endothelial dysfunction. The Kumamoto study suggests that reduced PPG is strongly associated with reductions in retinopathy and nephropathy. Finally, decreasing PPG in patients with IGT reduces the progression of diabetes. In conclusion, physicians should increase efforts to control PPG in order to further improve HbA(1c), and should also ensure close control of postprandial hyperglycaemic peaks so as to optimise patients' chances of avoiding cardiovascular complications. As for the prevention of CVD, further prospective intervention trials, powered to answer this question, are still required.