Glycaemic Control and Cardiovascular Outcomes in Diabetes : Review

RESUMO

While type 1 diabetes mellitus (DM) is characterised by insulin deficiency due to pancreatic beta-cell destruction; type 2 DM is characterised by a state of longstanding insulin resistance (IR); compensatory hyperinsulinaemia and varying degrees of elevated plasma glucose levels (PG); associated with clustering of cardiovascular (CV) risk and the development of macrovascular disease prior to the diagnosis of DM. Coronary artery disease (CAD) accounts for 70of mortality and morbidity in patients with diabetes. Studies in diabetes care have helped prevent or reduce microvascular complications in type 1 and 2 diabetes. However the same cannot be said about macrovascular disease. Despite all data concerning the association between diabetes and cardiovascular disease (CVD); the exact mechanism by which diabetes is linked to atherosclerosis is incompletely understood; and this is especially true in the case of hyperglycaemia. The positive effect of intensive glucose management in comparison to non-intensive glucose control is far from proven. The DCCT and UKPDS studies have shown that while glycaemic control is important for preventing long-term macrovascular complications; early glucose control is far more rewarding (metabolic memory). Later trials such as ACCORD; ADVANCE and VADT do not advocate tight glycaemic control. In fact; the ACCORD trial has shown increased mortality with tight glucose control. Tight glucose control may be beneficial in selected patients with short disease duration; long life expectancy and no CVD. In critically ill patients; a blood glucose target of 140-180 mg is fairly reasonable and achievable. The ESC/EASD guidelines of October 2013; like those of the ADA; AHA and ACC; continue to endorse a treatment target for glucose control in diabetes of HbAlc level 7; based predominantly on microvascular disease with acknowledged uncertainty regarding the effect of the intensive glucose control on CVD risk. Management of hyperglycaemia in diabetics should not be considered in isolation; diabetics require multifactorial intervention for hypertension; dyslipidaemia and microalbuminuria besides hyperglycaemia. In fact; the combined use of antihypertensives; aspirin and lipid-lowering agents makes it difficult to discern the beneficial effects of antihyperglycaemic therapy