Diabetes mellitus in older patients. Is tight blood glucose control warranted?

Diabetes mellitus is a major health problem in the older population, where it is mainly of the non-insulin-dependent type [i.e. non-insulin-dependent diabetes mellitus (NIDDM)]. Epidemiological evidence and extrapolation of trial data from patients with insulin-dependent diabetes mellitus (IDDM) suggests that improving glycaemic control reduces the risk of developing microvascular complications (i.e. retinopathy, nephropathy and neuropathy) and also slows the rate of progression of these complications in patients with early disease. Macrovascular morbidity and mortality is, however, more common than microvascular disease in the older population and the evidence that improved glycaemic control significantly reduces the impact of macrovascular disease is weak. Thus, the overall benefits of tight glycaemic control are less well defined in older patients, who tend to have NIDDM, than in younger patients with IDDM. There are small but significant risks associated with tight glycaemic control in the older patient, including potentially fatal hypoglycaemia with sulphonyl-ureas and/or insulin, and fatal metformin-induced lactic acidosis. Patients at especially high risk of these complications can, however, be identified and inappropriate pharmacological intervention can be avoided.