Beneficial and detrimental effects of intensive glycaemic control, with emphasis on type 2 diabetes mellitus

Diabetes mellitus is a major health problem in the world. Several clinical trials have shown that some of the major complications of diabetes mellitus can be partially prevented or delayed by intensive glycaemic control. However, there are benefits and risks in aiming for near normal blood glucose levels. Intensive glycaemic control delays the onset and progression of retinopathy, nephropathy and neuropathy. Epidemiological and observational studies have shown that cardiovascular events may be correlated with the severity and duration of diabetes mellitus, but major randomised trials have only shown weak and nonsignificant benefits of intensive glycaemic management in decreasing event rates. A modest improvement in lipid profile results from blood glucose control although, in the majority of cases, not enough to reach current targets. Detrimental effects of intensive glycaemic control include bodyweight gain and hypoglycaemia. Controversial issues in the management of patients with diabetes mellitus include the unproven increase in cardiovascular morbidity from sulphonylureas and hyperinsulinaemia, and the still unknown long term effects of newer oral antihyperglycaemic agents alone or in combination with traditional therapies (such as sulphonylureas and metformin). It is important to individualise management in setting glycaemic goals. Control of cardiovascular risk factors through blood pressure and lipid control and treatment with aspirin (acetylsalicylic acid) and ACE inhibitors have consistently shown benefits in the prevention of both macro- and microvascular complications in patients with diabetes mellitus; these measures deserve priority.