Pathophysiology of diabetes. A review of selected recent developments and their impact on treatment.

Recent developments in epidemiology, physiology, anatomy and molecular biology have greatly increased our knowledge of the aetiology and immunological mechanisms involved in diabetes mellitus. This understanding has, in turn, facilitated progress in the diagnosis and treatment of the disease. It is generally accepted that both genetic and environmental factors have a role in the pathogenesis of insulin- and non-insulin-dependent diabetes mellitus. The contribution of insulin resistance or decreased insulin secretion to the pathogenesis of non-insulin-dependent diabetes remains controversial but it is likely that both have a role to play. Counterregulatory hormones, principally adrenaline (epinephrine) and glucagon, prevent blood glucose levels falling to extreme levels by antagonising the effect of insulin hypoglycaemia, and inducing hepatic glucose production. Patients with insulin-dependent diabetes frequently exhibit impaired glucose counterregulation and, although its aetiology is uncertain in some patients, intensification of insulin therapy per se has been implicated. Secondary failure of oral hypoglycaemic agents in patients with non-insulin-dependent diabetes is a major and often inevitable problem, necessitating combined use of sulphonylurea and insulin in most patients. Recently, new treatments for patients with diabetes have been developed, including insulin analogues administered by a variety of novel methods, pancreatic grafts and transplantation of islet cells. Although promising, the clinical viability of these techniques remains to be demonstrated.